CN106161357B

CN106161357B - method, device and application server for realizing lawful interception in IMS network

Info

Publication number: CN106161357B
Application number: CN201510152294.4A
Authority: CN
Inventors: 魏磊
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2015-04-02
Filing date: 2015-04-02
Publication date: 2019-12-13
Anticipated expiration: 2035-04-02
Also published as: CN106161357A

Abstract

The invention discloses a method, a device and an application server for realizing lawful interception in an IMS network. The invention realizes the lawful monitoring in two calling scenes of pre-Transcoding and Transcoding after media negotiation failure through the static and dynamic trigger management mechanisms of the AS management entity to the O-AS or the T-AS, the LI-AS and the TC-AS, and enlarges the monitoring range of the lawful monitoring. The invention solves the problem that how to forward, copy and transmit media of calling and called parties in the current coding-decoding conversion calling scheme so as to realize lawful interception.

Description

Method, device and application server for realizing lawful interception in IMS network

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a method, an apparatus, and an application server for implementing lawful interception in an IMS network.

Background

The IP Multimedia Subsystem IMS (IP Multimedia Subsystem) is a Subsystem of IP Multimedia services proposed by The third Generation partnership Project (3 GPP). The IMS adopts a system architecture independent of an access technology, and has the following technical characteristics: session control based on Session Initiation Protocol (SIP), which is irrelevant to access, service and control are separated, and rich combined services are provided. The service and Control separation is mainly characterized in that the service and Control separation is realized by an Application Server (AS for short) and a Call Session Control Function (CSCF for short) respectively. SIP AS is an application server based on the SIP protocol, providing a wide range of value-added multimedia services, presence, messaging and conferencing services.

Fig. 1 is a typical call flow diagram in an IMS network according to the related art, and AS shown in fig. 1, after a call request message is sent to a Serving CSCF (S-CSCF), the S-CSCF triggers service requests in a Mobile Origination (MO) stage or a Mobile Termination (MT) stage to corresponding ASs respectively according to an Initial Filter criterion (iFC), and the ASs loops the service requests back to the S-CSCF after implementing service logic in the corresponding stage, and the S-CSCF continues a call processing procedure. According to different processed services, the AS can be logically divided into a calling AS (Originating Application Server, abbreviated AS O-AS) and a called AS (Terminating Application Server, abbreviated AS T-AS), wherein the O-AS processes the service of a calling side and is triggered by the S-CSCF at the MO stage; and the T-AS processes the called side service, and is triggered by the S-CSCF in the MT stage.

In IMS, different terminals or network elements use different codec formats (abbreviated as codecs), so that media negotiation between two parties may be unsuccessful, resulting in call failure. For example, a fixed network user generally supports g.711, while in a CDMA2000 network, a mobile terminal generally supports EVRC, and the two users call with different supported codec formats, so the call fails. For this, a network element is required to perform codec conversion (TC). TransCoding is defined in 5.14.4 and Annex P of TS23.228(8.8.0) of 3GPP, and is completed by using a Multimedia Resource Function (MRF), which is divided into pre-TransCoding and TransCoding after media negotiation failure.

fig. 2 is a flow chart of pre-TransCoding defined in 3GPP according to the related art, as shown in fig. 2, when the IMS system detects that the codes of the calling and called parties are different and TransCoding is required, the IMS system controls the MRF to prepare 2 pieces of media, where the opposite-end media of one piece of media is media description information SDP _ a of the calling user a, the codec format of the media is a format (codec-a) supported by the calling user a, and the codec format supported by the other piece of media is a codec format (codec-B) supported by the called party, and the system uses the two pieces of media prepared by the MRF to respectively complete media negotiation with the calling party and the called party. Since these two media are connected and TransCoding is possible on the MRF, i.e., both are interoperable. Therefore, after the MRF network element is used for TransCoding, the calling and called calls can be established. Such a call established using codec conversion is called a codec converted call.

The process of TransCoding after media negotiation failure is as follows: after the call is processed by the calling side network and the called side network, and the request message is sent to the called user, the called user does not support the codec format given by the calling side and returns an abnormal response message 488 or 606, indicating that the media codec format of the calling side is not accepted by the called side. The IMS system judges that the call needs to be subjected to TransCoding according to the abnormal response message given by the called user, and the subsequent flow of the IMS system is the same as the flow of the TransCoding in advance.

Lawful Interception (LI) is an information security technology that Law Enforcement Agencies (LEA) issue Interception request commands to network operators (NWO, Net Work Operator)/Access providers (AP, Access Provider)/Service providers (SvP, Service Provider) under the condition of approval by corresponding authorization authorities, and NWO/AP/SvP duplicates the related information of the intercepted object and sends the information to the LEA. In the aspect of assisting law enforcement agencies to fight against crimes, legal monitoring plays an extremely important role and is an important subject of network and information security.

Fig. 3 is an architecture diagram for implementing lawful interception of an application server according to the related art, and as shown in fig. 3, the interception of the application server in the IMS network generally adopts a network architecture conforming to the 3GPP European Telecommunication Standards Institute (ETSI) interception protocol. In this architecture, the submission interfaces (HI) between the operators (NWO/AP/SvP Domain) and the listening center (LEA Domain) are classified into HI1, HI2, and HI 3: the HI1 interface transmits related instructions of monitoring object setting, canceling, inquiring and the like; the HI2 interface transmits the communication Related event (IRI) Information of the monitored object; the HI3 interface delivers Content of Communication (CC) including signaling and media. Inside the operator (NWO/AP/SvP Domain), corresponding to the HI interface are X1, X2, X3 interfaces. The X1 and X2 interfaces are positioned between an application server and a Lawful Interception Gateway (LIG for short); the signaling interface of the X3 is positioned between the application server and the media gateway control function entity; the media interface of X3 is located between the listening media resource handler and the submission function gateway.

With the increasing use of multimedia communication by users, the types and codec formats of communication terminals are more abundant, and more communication between terminals requires codec conversion, so the application of the technology is becoming more and more extensive. In the codec conversion call, how to forward, copy and transfer the media of the calling and called parties so as to realize lawful interception becomes a difficult problem.

aiming at the problem of how to forward, copy and transmit media of a calling party and a called party in the current coding-decoding conversion calling scheme so as to realize lawful monitoring, an effective solution scheme is not provided at present.

Disclosure of Invention

The invention provides a method, a device and an application server for realizing lawful interception in an IMS (IP multimedia subsystem) network, aiming at the problem of how to forward, copy and transmit media of a calling party and a called party in the current coding-decoding conversion calling scheme so as to realize lawful interception.

according to an aspect of the present invention, the present invention provides a method for implementing lawful interception in an IMS network, which is applied to an application server AS management entity, wherein the method includes: after receiving a call request message initiated by a service-call session function entity (S-CSCF), determining an AS sequence to be triggered based on a preset condition; converting the call request message into an internal call request message, sequentially triggering each AS in the AS sequence to be triggered, sequentially sending the internal call request message to each AS, and receiving an internal call request response message returned by each AS after each AS is triggered; converting the received internal call request response message returned by the last AS into a call request response message, and sending the call request response message to the S-CSCF; and managing the transmission and sending of subsequent call messages after the call request response message is carried out, and establishing normal conversation after the calling side and the called side are converted through coding and decoding through media negotiation, wherein the conversation is monitored.

Preferably, the managing, through media negotiation, enables the calling and called sides to establish a normal call after codec conversion, including: and finishing the media negotiation among the calling and called media, the monitoring media and the coding and decoding conversion media, so that the calling and called users establish normal conversation after coding and decoding conversion.

preferably, the preset conditions include: whether the call request message carries a start call MO indication or a final call MT indication, whether a calling side service is a multi-party call service, whether a calling user or a called user is monitored, or whether pre-codec conversion is performed is determined by judging whether a media codec of the called user and the calling user have intersection.

Preferably, determining an AS sequence to be triggered based on a preset condition includes: if the call request message carries MO indication, adding a calling application server O-AS into the AS sequence to be triggered, and if the call request message carries MT indication, adding a called application server T-AS into the AS sequence to be triggered; if the calling side service is a multi-party call service, the coding and decoding conversion application server TC-AS is not added into the AS sequence to be triggered, and the judgment of whether to perform the pre-coding and decoding conversion is not performed; determining whether to trigger and monitor an application server LI-AS based on whether a calling user or a called user is monitored, if so, adding the LI-AS into the AS sequence to be triggered, and if not, not adding the LI-AS into the AS sequence to be triggered; and determining whether to trigger a coding-decoding conversion application server TC-AS based on whether to carry out pre-coding-decoding conversion, if so, adding the LI-AS into the AS sequence to be triggered, and if not, not adding the TC-AS into the AS sequence to be triggered.

Preferably, whether the pre-codec conversion is required is determined by: and judging whether the pre-coding and decoding conversion is needed or not according to the media template of the attribute of the service user recorded in the inquired database or the media template of the called user number segment recorded in the number analysis.

preferably, after the AS management entity makes the calling and called sides establish a normal call after performing codec conversion, the method further includes: under an abnormal call scene, dynamically triggering LI-AS or TC-AS; adding the dynamically triggered AS into the triggered AS sequence and reordering; and managing the transmission and sending sequence of the subsequent messages to complete the whole call.

preferably, in an abnormal call scenario, dynamically triggering the LI-AS or the TC-AS includes: dynamically triggering LI-AS according to a special scene in the calling process or dynamically triggering TC-AS according to the received abnormal response message; the special scene is a scene when the normal call is abnormal.

Preferably, the call request message received is: a call request message initiated by said S-CSCF and decoded and adapted by a protocol adaptation entity.

According to another aspect of the present invention, the present invention further provides an apparatus for implementing lawful interception in an IMS network, which is applied to an AS management entity, wherein the apparatus includes: the system comprises a sequence establishing module, a sequence determining module and a triggering module, wherein the sequence establishing module is used for determining an AS sequence to be triggered based on a preset condition after receiving a call request message initiated by a service-call session function entity (S-CSCF); the static trigger module is used for converting the call request message into an internal call request message, sequentially triggering each AS in the AS sequence to be triggered, sequentially sending the internal call request message to each AS, and receiving an internal call request response message returned by each AS after the triggering of each AS is completed; then converting the received internal call request response message returned by the last AS into a call request response message, and sending the call request response message to the S-CSCF; and the call establishing module is used for transmitting and sending subsequent call messages after the call request response message, establishing normal call after the calling side and the called side are converted through coding and decoding through media negotiation, and monitoring the call.

preferably, the sequence establishing module determines an AS sequence to be triggered based on a preset condition, including: if the call request message carries MO indication, adding a calling application server O-AS into the AS sequence to be triggered, and if the call request message carries MT indication, adding a called application server T-AS into the AS sequence to be triggered; if the calling side service is a multi-party call service, the coding and decoding conversion application server TC-AS is not added into the AS sequence to be triggered, and the judgment of whether to perform the pre-coding and decoding conversion is not performed; determining whether to trigger and monitor an application server LI-AS based on whether a calling user or a called user is monitored, if so, adding the LI-AS into the AS sequence to be triggered, and if not, not adding the LI-AS into the AS sequence to be triggered; and determining whether to trigger a coding-decoding conversion application server TC-AS based on whether to carry out pre-coding-decoding conversion, if so, adding the LI-AS into the AS sequence to be triggered, and if not, not adding the TC-AS into the AS sequence to be triggered.

preferably, the apparatus further comprises: the dynamic triggering module is used for dynamically triggering LI-AS or TC-AS by the AS management entity under an abnormal call scene; adding the dynamically triggered AS into the triggered AS sequence and reordering; and managing the transmission and sending sequence of the subsequent messages to complete the whole call.

Preferably, the dynamic trigger module is further configured to dynamically trigger the LI-AS according to a special scene in a call process, or dynamically trigger the TC-AS according to a received abnormal response message; the special scene is a scene when the normal call is abnormal.

According to another aspect of the present invention, the present invention also provides an application server in an IMS network, wherein the application server includes: the system comprises an AS management entity, a protocol adaptation entity, a service application server O-AS or T-AS, a monitoring application server LI-AS and a coding-decoding conversion application server TC-AS which are logically independent from each other, wherein the AS management entity is used for triggering logically related and independent O-AS, T-AS, LI-AS and/or TC-AS according to a static trigger and dynamic trigger management mechanism; storing and managing the relevant information of the whole call; managing the sending and delivery of call messages; the protocol adaptation entity comprises an SIP protocol subsystem and an H.248 protocol subsystem and is used for decoding messages of other network elements received by the application server, converting the messages into internal messages and sending the internal messages to the AS management entity; the O-AS and the T-AS are used for executing the value-added service logic of the calling side or the called side of the service user; the LI-AS is used for executing monitored service logic; the TC-AS is used for executing the business logic of coding and decoding conversion, controlling a coding and decoding conversion media resource processor to prepare coding and decoding conversion media and negotiating the media of the calling and called users.

the invention has the following beneficial effects:

1) the invention realizes the lawful monitoring in two calling scenes of pre-Transcoding and Transcoding after media negotiation failure through the static and dynamic trigger management mechanisms of the AS management entity to the O-AS or the T-AS, the LI-AS and the TC-AS, and enlarges the monitoring range of the lawful monitoring.

2) In the technical scheme provided by the invention, each AS is logically independent from each other, the structure is clear, the module coupling is low, and the maintenance and the expansion are convenient.

3) In the technical scheme provided by the invention, only one application server is presented for the S-CSCF, and the service, monitoring and coding and decoding conversion can be realized by one-time triggering, so that the message interaction among network elements is reduced, and the running performance and efficiency of the whole IMS system are ensured not to be reduced.

4) The method provided by the invention does not change the processing rule of the IMS system, does not cause any influence on the existing IMS system, and effectively ensures the implementability and backward compatibility of the method.

The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.

Drawings

Fig. 1 is a typical call flow diagram in an IMS network according to the related art;

fig. 2 is a flowchart of pre-TransCoding defined in 3GPP according to the related art;

FIG. 3 is an architecture diagram for lawful interception of application servers according to one implementation of the related art;

fig. 4 is a flowchart of a method for implementing lawful interception in an IMS network according to a first embodiment of the present invention;

Fig. 5 is a block diagram of an apparatus for implementing lawful interception in an IMS network according to a second embodiment of the present invention;

fig. 6 is a schematic structural diagram of an application server in an IMS network according to a third embodiment of the present invention;

Fig. 7 is a flowchart of a method for implementing lawful interception in an IMS network according to a fourth embodiment of the present invention;

fig. 8 is a flowchart of a method for implementing lawful interception in an IMS network according to a fifth embodiment of the present invention;

Fig. 9 is a flowchart of a method for implementing lawful interception in an IMS network according to a sixth embodiment of the present invention;

Fig. 10 is a flowchart of a method for implementing lawful interception in an IMS network according to a sixth embodiment of the present invention;

Fig. 11 is a flowchart of a method for implementing lawful interception in an IMS network according to a seventh embodiment of the present invention;

Fig. 12 is a flowchart of a method for implementing lawful interception in an IMS network according to an eighth embodiment of the present invention;

fig. 13 is a media connection diagram of an eighth embodiment of the present invention, where the method for lawful interception is implemented in an IMS network.

Detailed Description

In order to solve the problem of how to forward, copy and transmit media of a calling party and a called party in the current coding-decoding conversion calling scheme so as to realize lawful interception, the invention provides a method, a device and an application server for realizing lawful interception in an IMS network, and the invention is further described in detail below by combining the attached drawings and the embodiment. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.

in the invention, an Application Server (AS) comprises a service Application Server (O-AS or T-AS), a monitoring Application Server (LI-AS), a coding-decoding conversion Application Server (TC-AS), a protocol adaptation entity and an AS management entity, wherein the service Application Server (O-AS or T-AS) is logically independent from the monitoring Application Server (LI-AS). The AS management entity may statically trigger the AS according to a certain sequence when receiving the call request message, or may dynamically trigger the corresponding AS according to a certain principle in some subsequent scenarios. The AS are mutually independent, and the AS management entity uniformly performs trigger management, so that the structure is clear, flexible and easy to realize; the AS management entity and each AS use internal messages to realize interaction, so that the system overhead is low and the operation efficiency is high.

example one

fig. 4 is a flowchart of a method for implementing lawful interception in an IMS network according to an embodiment of the present invention, as shown in fig. 4, the method includes the following steps:

Step S402, after receiving a call request message initiated by S-CSCF, an AS management entity determines an AS sequence to be triggered based on a preset condition; wherein the call request message is: the call request message, originated by the S-CSCF, decoded and adapted by the protocol adaptation entity.

step S404, the AS management entity converts the call request message into an internal call request message, sequentially triggers each AS in the AS sequence to be triggered, sequentially sends the internal call request message to each AS, and receives an internal call request response message returned by each AS after the triggering of each AS is completed; and the AS management entity converts the received internal call request response message returned by the last AS into a call request response message and sends the call request response message to the S-CSCF.

Step S406, the AS management entity manages the transmission and sending of the subsequent call message after the call request response message is carried out, and through media negotiation, the calling and called sides establish normal conversation after the coding and decoding conversion, and the conversation is monitored.

in this embodiment, the preset conditions in step S402 include: whether the call request message carries a start call MO indication or a final call MT indication, whether the calling side service is a multi-party call service, whether a calling subscriber or a called subscriber is monitored, or whether pre-codec conversion is performed is determined by judging whether the media codec of the called subscriber and the calling subscriber have intersection.

In step S402, determining an AS sequence to be triggered based on different preset conditions, including the following preferred embodiments:

1) If the calling request message carries MO indication, adding a calling application server O-AS into an AS sequence to be triggered, and if the calling request message carries MT indication, adding a called application server T-AS into the AS sequence to be triggered;

2) If the calling side service is a multi-party call service, the TC-AS is not added into the AS sequence to be triggered, and the judgment of whether to perform pre-coding and decoding conversion is not performed;

3) Determining whether to trigger and monitor an application server LI-AS based on whether a calling user or a called user is monitored, if so, adding the LI-AS into an AS sequence to be triggered, and if not, not adding the LI-AS into the AS sequence to be triggered;

4) And determining whether to trigger a coding-decoding conversion application server TC-AS based on whether to carry out pre-coding-decoding conversion, if so, adding the LI-AS into the AS sequence to be triggered, and if not, not adding the TC-AS into the AS sequence to be triggered. Wherein, whether the pre-coding/decoding conversion is needed or not can be judged by the following preferred embodiments: the AS management entity judges whether the pre-coding and decoding conversion is needed or not according to the media template of the attribute of the service user recorded in the inquired database or the media template of the called user number segment recorded in the number analysis.

In step S406, the AS management entity manages to establish a normal call after the calling and called sides are converted by encoding and decoding through media negotiation, including: the AS management entity completes the media negotiation between the calling and called media, the monitoring media and the coding and decoding conversion media, so that the calling and called users establish normal conversation after coding and decoding conversion.

Step S406, after the AS management entity makes the calling and called sides establish normal communication after codec conversion, the method further includes:

1) And under the abnormal call scene, the AS management entity dynamically triggers the LI-AS or the TC-AS. Specifically, the AS management entity dynamically triggers LI-AS according to a special scene in the calling process or dynamically triggers TC-AS according to a received abnormal response message; the special scene is a scene when the normal call is abnormal.

2) The AS management entity adds the dynamically triggered AS to the triggered AS sequence and reorders the sequence.

3) The AS management entity manages the transmission and sending sequence of the subsequent messages and completes the whole call.

example two

fig. 5 is a block diagram of an apparatus for implementing lawful interception in an IMS network according to a second embodiment of the present invention, and AS shown in fig. 5, the apparatus is applied to an AS management entity, and the apparatus includes:

the sequence establishing module 10 is configured to determine, based on a preset condition, an AS sequence to be triggered after receiving a call request message initiated by an S-CSCF;

the static trigger module 20 converts the call request message into an internal call request message, sequentially triggers each AS in the AS sequence to be triggered, sequentially sends the internal call request message to each AS, and receives an internal call request response message returned by each AS after the triggering of each AS is completed; then the received internal call request response message returned by the last AS is converted into a call request response message and sent to the S-CSCF;

the call establishing module 30 is configured to transmit and send a subsequent call message after the call request response message, and through media negotiation, the calling and called sides establish a normal call after codec conversion, and the call is monitored.

in this embodiment, the preset conditions include: whether the call request message carries a start call MO indication or a final call MT indication, whether the calling side service is a multi-party call service, whether a calling subscriber or a called subscriber is monitored, or whether pre-codec conversion is performed is determined by judging whether the media codec of the called subscriber and the calling subscriber have intersection.

Preferably, the sequence establishing module determines an AS sequence to be triggered based on a preset condition, including:

If the calling request message carries MO indication, adding a calling application server O-AS into an AS sequence to be triggered, and if the calling request message carries MT indication, adding a called application server T-AS into the AS sequence to be triggered;

If the calling side service is a multi-party call service, the TC-AS is not added into the AS sequence to be triggered, and the judgment of whether to perform pre-coding and decoding conversion is not performed;

Determining whether to trigger and monitor an application server LI-AS based on whether a calling user or a called user is monitored, if so, adding the LI-AS into an AS sequence to be triggered, and if not, not adding the LI-AS into the AS sequence to be triggered;

and determining whether to trigger a coding-decoding conversion application server TC-AS based on whether to carry out pre-coding-decoding conversion, if so, adding the LI-AS into the AS sequence to be triggered, and if not, not adding the TC-AS into the AS sequence to be triggered.

The above-mentioned device still includes: the dynamic triggering module is used for dynamically triggering LI-AS or TC-AS by the AS management entity under an abnormal call scene; adding the dynamically triggered AS into the triggered AS sequence and reordering; and managing the transmission and sending sequence of the subsequent messages to complete the whole call.

The dynamic trigger module is further used for dynamically triggering LI-AS according to a special scene in the calling process or dynamically triggering TC-AS according to the received abnormal response message; the special scene is a scene when the normal call is abnormal.

EXAMPLE III

Fig. 6 is a schematic structural diagram of an application server in an IMS network according to a third embodiment of the present invention, and as shown in fig. 6, the application server includes: AS management entity, protocol adaptation entity, and logically mutually independent service application server O-AS or T-AS, monitoring application server LI-AS, and codec conversion application server TC-AS, wherein,

And the protocol adaptation entity comprises a SIP protocol subsystem and an H.248 protocol subsystem. Decoding of messages of other network elements received by the application server is completed, and the messages are converted into internal messages to be sent to the AS management entity; and completes the protocol coding of the message that the application server needs to send to other network elements.

The AS management entity mainly completes the following functions: 1) triggering logically related independent O-AS or T-AS, LI-AS and TC-AS according to the static trigger and dynamic trigger management mechanism; 2) storing and managing the related information of the whole call, including call progress information, calling and called media description information, etc.; 3) managing the sending and delivery of call messages;

O-AS or T-AS, service application server, executing value-added service logic of calling side or called side of service user. The service of the calling side mainly comprises number display type (calling number display limitation, connected number display), authority type service (calling limitation, called destination code connection) and the like; the services of the called side include: forwarding class (unconditional forwarding, busy forwarding, no answer forwarding, etc.), number display class (calling number display, etc.), authority class, called one-number-call, color ring, no disturbance, etc.

And determining the role of the service application server in the triggering call according to the MO or MT instruction carried in the call request message initiated by the S-CSCF. If the carried indication is MO, the current trigger is MO stage trigger, namely calling side trigger, the role of the AS is O-AS at the moment, and the AS is used for executing calling side service of a service user; if the carried indication is MT, the present trigger is MT stage trigger, namely called side trigger, then the role of AS is T-AS, which is used to execute the calling side service of the service user. The O-AS or T-AS executes relevant value-added service logic according to the registration condition of the relevant service in the system database or certain messages sent to the system by the user executing certain operations in the calling process.

The LI-AS lawful interception application server executes the intercepted business logic. The method comprises the following steps: setting a monitoring object; reporting communication related events; the control monitor media resource processor prepares to monitor media, and negotiates with the monitor submitting gateway and with the media of the calling and called users, and transmits communication content.

TC-AS, coding-decoding conversion application server, and business logic for executing coding-decoding conversion. Controlling the codec conversion media resource processor to prepare the codec conversion media and the negotiation of the media of the calling and called users.

the technical solution of the present invention is described in detail below with reference to several preferred embodiments and accompanying drawings.

Example four

Fig. 7 is a flowchart of a method for implementing lawful interception in an IMS network according to a fourth embodiment of the present invention, AS shown in fig. 7, this embodiment provides an AS management entity to statically and dynamically trigger an O-AS or a T-AS, an LI-AS, and a TC-AS, store and manage relevant information of a whole call including call progress information and calling and called media description information, and manage sending and transferring of a call message, so AS to implement a process of lawful interception of a codec converted call, which specifically includes the following steps:

step S701, an AS management entity receives a call request message initiated by an S-CSCF, and the message carries an MO or MT instruction.

Specifically, the S-CSCF triggers the service request in the MO stage or the MT stage to the AS according to the iFC rule, and the Route field of the call request message carries a mode parameter to distinguish: if mode is MO, it indicates that the current trigger is MO stage trigger, i.e. calling side trigger, then the role of the AS is O-AS at this time, and is used to execute the calling side service of the service user; if the mode is MT, it indicates that the present trigger is MT phase trigger, i.e. called side trigger, then the role of the AS is T-AS at this time, and is used to execute the called side service of the service user. The call request message is sent to the AS management entity after being decoded and adapted by the protocol adaptation layer entity of the AS.

step S702, the AS management entity judges and analyzes according to the indication of MO or MT, whether the multi-party call service is available, whether the monitoring is available, whether the pre-coding and decoding conversion is needed, and the like, and determines an AS sequence to be statically triggered.

The MO indication indicates that the present trigger is MO stage trigger, that is, calling side trigger, and the role of the AS is O-AS at this time, which is used to execute calling side service of the service user and needs to trigger the O-AS. The MT indication indicates that the present trigger is MT phase trigger, i.e. called side trigger, and the role of the AS is T-AS at this time, which is used to execute the calling side service of the service user and needs to trigger T-AS.

The multi-party call service needs to be triggered to a conference media resource processor in advance to prepare conference media resources, and the codecs supported by the conference media resource processor are rich enough, so that the AS does not need to perform TransCoding operation on a calling party and a called party; meanwhile, aiming at monitoring the multi-party call service, all users can be monitored as long as the chairman user of the conference is monitored. The two characteristics make it necessary to process the multi-party call service and the non-multi-party call service separately when the AS management entity triggers and manages the O-AS, the LI-AS and the TC-AS.

And the AS management entity judges whether to trigger the LI-AS according to whether the user is under control, and if the triggering is needed, the LI-AS is added into the AS sequence to be triggered.

And the AS management entity judges whether to trigger the TC-AS according to the media template of the attribute of the service user recorded in the inquired database or the media template of the called user number segment recorded in the number analysis, and if the TC-AS needs to be triggered, the TC-AS is added into an AS sequence to be triggered.

And the AS management entity determines an AS sequence to be statically triggered according to the judgment and analysis. The sequence of AS in the sequence depends on the sequence of AS logic judgment, and the sequence of AS logic judgment mainly considers the different stages of the call and the different characteristics of the calling side service and the called side service, so AS to avoid repeated, crossed, repeated and unnecessary AS triggering AS much AS possible, reduce the interaction of messages and avoid the waste of resources.

Step S703, the AS management entity triggers the AS in the AS sequence in turn to complete the preparation of monitoring media and encoding and decoding conversion media; and after the static trigger is finished, the call request message is looped back to the S-CSCF, and the call is continued.

The step is that the AS management entity triggers the AS in sequence, the AS executes the corresponding service logic, and the AS notifies the AS management entity after the execution is finished. The O-AS or T-AS executes relevant value-added service logic according to the registration condition of the relevant service in the system database or certain messages sent to the system by the user executing certain operations in the calling process. The LI-AS mainly completes the report of the communication related events and reserves the monitoring channel resources on the LI MRFP, so that the media of the calling and called users are forwarded by the LIMRFP. The monitoring center monitors the monitoring channel to monitor the media of the calling and called users. The TC-AS mainly completes the function of controlling the coding and decoding conversion resource processor to prepare the TransCoding media resource.

the AS management entity stores and manages the related information of the whole call, including call progress information, calling and called media description information and the like. When a certain AS is triggered, the related information of the call is sent to the AS, the AS executes respective service logic to modify the related information of the call and then sends the modified information back to the AS management entity, and the AS management entity updates and stores the information.

step S704, the AS management entity manages the transmission and sending of subsequent call messages such AS ringing and answering after the call request message, and completes the media negotiation between the calling and called media, the monitoring media and the codec conversion media, so that the calling and called parties can establish a call after codec conversion, and the call can be monitored.

according to the principle of reverse serial, the AS management entity sends the subsequent call messages such AS ringing, answering and the like after the call request message to each AS in turn according to the reverse direction of the triggered AS sequence. The TC-AS and the LI-AS respectively indicate the TC MRFP and the LI MRFP to update the media description information of the opposite terminal called side of the coding-decoding conversion media and the monitoring media, and negotiate with the calling media and the called media, so that the media request and response balance on each network element in the whole calling process is achieved, the calling media and the called media can establish a call after the coding-decoding conversion, and the call can be monitored.

Step S705, the AS management entity dynamically triggers LI-AS according to the special scene in the calling process or dynamically triggers TC-AS according to the received abnormal corresponding message; the AS management entity adds the dynamically triggered AS to the triggered AS sequence, reorders the AS sequence, manages the transmission and sending sequence of the subsequent messages and completes the whole call.

the method specifically comprises the following steps that an AS management entity dynamically triggers LI-AS according to a special scene in a calling process, wherein the scene mainly comprises the following steps: and the O-AS abnormally plays the sound to the calling user. According to the sequence of the AS management entity for statically triggering each AS, if the service of the calling side is not the multi-party call service during MO triggering, the LI-AS is positioned behind the O-AS; at this time, in the process of executing the service logic by the O-AS, if the O-AS is required to abnormally play the sound to the calling party, since the LI-AS is not triggered before, the LEA cannot monitor the sound, and therefore the LI-AS must be dynamically triggered at this time so AS to monitor the sound.

the TC-AS needs to support two modes of precoding in advance and TransCoding after media negotiation failure, and the actual corresponding AS management entity has two modes of static triggering in advance and dynamic triggering by subsequent response message. Because the media capability template of the called user is not configured in the system or the configuration is wrong, the pre-TransCoding is not executed, and when the subsequent call request is sent to the called user and the response message of the called user 488 or 606 indicates that the call cannot be established due to different codecs, the TC-AS needs to be dynamically triggered to perform codec conversion, so that the calling party and the called party can communicate. The 488 or 606 response message returned by the caller or the callee to the media update request message during the call will also trigger the TC-AS.

The AS management entity adds the dynamically triggered AS to the triggered AS sequence and reorders the sequence to ensure that the message in the subsequent calling process passes through the dynamically triggered AS.

the embodiment provides a method for realizing lawful interception in an IMS network, which realizes lawful interception in two calling scenes of pre-TransCoding and TransCoding after media negotiation failure under the effective management of an AS management entity on O-AS or T-AS, LI-AS and TC-AS static and dynamic triggering modes through the steps.

EXAMPLE five

fig. 8 is a flowchart of a method for implementing lawful interception in an IMS network according to a fifth embodiment of the present invention, and AS shown in fig. 8, this embodiment provides an entire flow that an AS management entity starts from receiving a call request message initiated by an S-CSCF, determines whether LI-AS and TC-AS need to be triggered, determines an AS sequence to be triggered, sequentially triggers ases in the AS sequence, completes static triggering of the AS sequence, and finally loops back the call request message to the S-CSCF. The method specifically comprises the following steps:

Step S801, the AS management entity receives a call request message initiated by the S-CSCF, where the message carries an indication of the MO or the MT. The S-CSCF triggers the service request of the MO stage or the MT stage to the AS according to the iFC rule, and the call request message is sent to the AS management entity after being decoded and adapted by a protocol adaptation layer entity of the AS.

Step S802, the AS management entity judges the trigger request of the S-CSCF at this time AS the trigger of the calling side. The Route field in the call request message carries a mode parameter of mode MO, which indicates that the present trigger is MO phase trigger, i.e. the calling side trigger, and the role of the AS is O-AS at this time, which is used to execute the calling side service of the service user. Value added services of the calling subscriber, such as calling number display restriction, calling restriction, SUBSCRIBE (call back in busy), three-way call, conference, call forwarding and the like, need to be completed.

In step S803, the AS management entity determines that the calling side service is a non-multiparty call service. And after judging that calling side triggering is needed, the AS management entity inquires the service information of the calling service user according to the user identification. For the service of the calling side, except the multi-party call service, the service can not be forked to simultaneously initiate multi-path call. The multi-party call service needs to be triggered to a conference media gateway in advance to prepare conference media resources, and the codecs supported by the conference media gateway are rich enough, so that an AS (application server) is not needed to perform TransCoding operation on a calling party and a called party; meanwhile, aiming at monitoring the multi-party call service, all users can be monitored as long as the chairman user of the conference is monitored. The two characteristics make it necessary to process the multi-party call service and the non-multi-party call service separately when the AS management entity triggers and manages the O-AS, the LI-AS and the TC-AS.

Step S804, the AS management entity determines that the calling user is monitored. The monitoring center deploys the user to be monitored through a deployment command, and after the deployment command is sent to the AS, the AS stores the user identification of the deployed user in a database background of the AS in a data table mode. In this step, the AS management entity queries the background database, and matches records in the database table according to the user identification so AS to determine whether the service calling is monitored or not. If the calling subscriber is monitored, triggering the LI-AS; if not, there is no need to trigger the LI-AS. In this step the calling subscriber is monitored and LI-AS needs to be triggered, thus adding LI-AS to the AS sequence to be triggered.

The partial flow (i.e. the flow not monitored) not marked with NO in this step is a simplified flow of this example, and can be implemented with reference to this example. The same applies to the flow in which NO is not indicated in the other steps of determination in fig. 8.

In step S805, the AS management entity determines that the codecs supported by the calling party and the called party are different. When the called party is subjected to number analysis, the media coding capability of the calling party carried in the calling message is compared with the called media coding capability in a called media capability template in the called party number section configuration, if no intersection exists, the calling party and the called party are different in coding and decoding, and the service logic of TC-AS needs to be executed so AS to use TC MFRP to perform media coding and decoding conversion. In the step, the encoding and decoding of the calling party and the called party are different, and the TC-AS needs to be triggered, so that the TC-AS is added into an AS sequence to be triggered.

step S806, the AS management entity determines that the AS sequences to be statically triggered are O-AS, LI-AS and TC-AS in sequence.

Since each AS is triggered, controlled and managed by the AS management entity, and each AS transmits the call related information to the AS management entity, corresponding services can be realized AS long AS the AS is triggered to the corresponding AS when needed, no matter how complex call models and scenes exist. This may result in triggering each AS, which may be repeated, interleaved, multiple times, and logically chaotic. How to reasonably determine the static trigger sequence and reduce repeated, crossed and multiple logic disordered triggers while ensuring the basic call scene and considering the special call scene is important.

The current trigger is the trigger of the calling side, and the role of the AS is O-AS; the calling side service is a non-multi-party communication service, which indicates that no conference media resource participates in the call, and further needs to judge whether the encoding and decoding of the calling party and the called party are different; the calling party is monitored, and the LI-AS needs to be triggered; the calling and called codes are different, which indicates that TC-AS needs to be triggered; and by combining the points, the AS management entity determines that the AS sequences to be statically triggered are O-AS, LI-AS and TC-AS in sequence. The advantage of this static trigger sequence is:

1) This order may reduce unnecessary triggering of the TC-AS. Calling side calling authentication service such AS calling limit service, black and white list service, etc. firstly triggering O-AS, after authentication, finding that calling user has no right to call out, then it is no longer necessary to trigger TC-AS subsequently. If the TC-AS is triggered first in each call, the TC MRFP is indicated to prepare the media resources, and the user is not authorized to call when the O-AS is triggered later, a release message is also sent to the TC-AS to release the previously prepared media resources. Therefore, the TC-AS is placed behind the O-AS, unnecessary triggering of the TC-AS can be reduced, thereby avoiding wasting the media resources of the TC MRFP, reducing message interaction and improving the system performance.

2) This sequence facilitates the monitoring of call forwarding-like traffic. This will be explained in detail below. User a is registered with the call forwarding service and has been provisioned by the LEA as a listening user. In the conversation process of the user A and the user B, the switching service user A initiates switching to the user C, after the user A and the user C have a conversation, the user A hangs up, and the user B and the user C continue to have a conversation. The call between user B and user C still needs to be monitored according to the monitoring requirement. If the O-AS is triggered before the LI-AS, according to the principle of the subsequent response message reverse serial sending, the user A on-hook release message is sent to the LI-AS first, the LI-AS can immediately control the calling side to monitor the media and establish connection with the media of the user B to enter the call at the moment, the media of the user B is sent to the LEA through the monitoring channel, then the release information is transmitted to the AS management entity and the O-AS, and the O-AS completes the release process of the user A. Under the same situation, if the a hang-up release message is sent to the O-AS first, the normal service logic of the O-AS releases the call of the user a, and at this time, the call is not controlled by the LI-AS yet, and the user B about to enter the call is not connected to the monitoring channel, so that the monitoring of the user B and the user C cannot be realized. If monitoring the conversation between the user B and the user C is to be realized, the O-AS adds logic judgment here, triggers to the LI-AS and triggers to the O-AS again through the transmission of the AS management entity, and the cross triggering increases the transmission of internal messages, is disordered in logic and is difficult to manage the timer.

3) The sequence is convenient for reporting the monitored communication events in the value added service implementation process. The codec conversion function is only directed at the operation of the media, and the monitoring needs to complete the reporting of the media and the communication event at the same time. After the O-AS detects a certain communication event, in order to facilitate the LI-AS to realize the reporting of the communication event in the monitoring service logic, the LI-AS needs to be triggered after being close to the O-AS.

Step S807, the AS management entity triggers the O-AS, and the O-AS notifies the AS management entity after executing the service logic.

The method specifically comprises the steps that an O-AS related data area is created for an AS management entity, call related information is sent to the O-AS, after the O-AS executes a calling side service sequence of a calling user, the AS management entity is informed that the O-AS is triggered, and the modified call related information is sent back to the AS management entity. The calling service sequence of the calling service user may include: number display class (calling number display limit, connected number display), permission class service (calling limit, called destination code connection), calling one-number-call, color image, new service registration, activation, etc., SUBSCRIBE (busy call back), call with access code (e.g., answer, cross, connection), call hold, refer class (call connection, call transfer), etc.

The O-AS executes the process of the calling side service: (calling number display restriction service is taken as an example):

1) And the O-AS searches the service attribute of the calling user and finds that the calling user registers the calling number display restriction service.

2) The O-AS inserts a Privacy header field into the call request message and sets the value to be id; while modifying the From field to anonymous.

And after the O-AS completes the calling service logic, sending a call progress message to an AS management entity.

step S808, the AS management entity triggers LI-AS, and the LI-AS notifies the AS management entity after executing the service logic.

The method comprises the following steps that an LI-AS related data area is created for an AS management entity, a monitoring request and call related information are sent to an LI-AS, the LI-AS informs the AS management entity that the LI-AS is triggered after the monitoring service logic is executed, and modified call related information, particularly media description information of a calling party, is sent back to the AS management entity.

The process of LI-AS executing listening service logic is:

1) The AS management entity sends the monitoring request and the call related information to LI-AS, wherein the contained media description information of the calling party is the media description information SDP _ A of the user A, and the media coding format is codec-A.

2) The H.248 subsystem of the LI-AS control protocol adaptation layer entity sends 2 ADD operation commands to the LI MRFP network element, and instructs the LI MRFP network element to ADD two RTP in the same Context, wherein the opposite end media description information of one RTP points to the media description information SDP _ A of the calling A. LI MRFP replies that LI-AS has successfully created two RTP's, which for descriptive convenience are referred to in this example AS RTP1_ LI and RTP2_ LI, respectively, where the peer media description of RTP1_ LI points to the media description of caller a, SDP _ a.

3) The h.248 subsystem of the LI-AS control protocol adaptation layer entity issues again 2 ADD operation commands to the LI MRFP network element instructing the LI MRFP network element to ADD two RTPs in the same Context AS in step 2. The LI MRFP reply LI-AS creates two RTP successes, RTP1_ COPY and RTP2_ COPY, respectively.

4) The H.248 subsystem of the LI-AS control protocol adaptation layer entity sends out a Modify operation command to the LI MRFP network element, and the RTP1_ COPY only receives the media stream from the RTP1_ LI and the RT2_ COPY only receives the media stream from the RTP2_ LI by means of Topology { RTP1_ LI, RTP1_ COPY, Oneway }, Topology { RTP2_ LI, RT2_ COPY, Oneway } }.

5) The LI-AS sends a call request INVITE message to a media gateway control function entity, and the message carries media description information of corresponding CCCID1 and RTP1_ COPY. The media gateway control function entity instructs the submitting function gateway MGW to add RTP1_ MGW, and returns a200 OK response message carrying media description information of RTP1_ MGW. The LI-AS sends a CC message to the LIG informing the listening media channel 1 that it is open. Similarly, an RTP2_ MGW is created and a CC message is sent to the LIG informing the listening media channel 2 to be opened.

6) The H.248 subsystem of the LI-AS control protocol adaptation layer entity sends two Modify operation commands to the LI MRFP network element respectively, modifies the opposite end media description information of RTP1_ COPY into the media description information of RTP1_ MGW, and modifies the opposite end media description information of RTP2_ COPY into the media description information of RTP2_ MGW.

7) and the LI-AS sends the updated media description information and the call progress message to the AS management entity together, and informs the AS management entity that the execution of the service logic of the LI-AS is completed.

8) The AS management entity replaces the media description information of the caller with the media description information of RTP2_ LI.

Through the above operation, the LI-AS creates and reserves the listening channel resource on the LI MRFP, and completes the media negotiation with the listening and submitting function gateway. The LI-AS sends the modified call related information, in particular the media description information of the caller, back to the AS management entity. The AS management entity replaces the media description information of the calling side with the media description information of RTP2_ LI.

step S809, the AS management entity triggers TC-AS, and the TC-AS notifies the AS management entity after executing the service logic.

The method specifically comprises the steps of establishing a TC-AS related data area for an AS management entity, sending call related information to a TC-AS, informing the AS management entity that the TC-AS is triggered after the TC-AS executes a TransCoding service logic, and returning the modified call related information, particularly media description information of a calling side, to the AS management entity.

The TC-AS executes a Transcoding service logic process:

1) The AS management entity sends a Transcoding request and call related information to the TC-AS, wherein the contained media description information of the calling party is the media description information of RTP2_ LI.

2) The H.248 subsystem of the TC-AS control protocol adaptation layer entity sends an ADD operation command to the TC MRFP network element, the TC MRFP network element is indicated to ADD an RTP, the opposite-end media description information points to the media description information of the RTP2_ LI, and the TC MRFP network element replies that the TC-AS creates the RTP successfully. For convenience of description, this RTP is referred to as RTP1_ TC.

3) The H.248 subsystem of the TC-AS control protocol adaptation layer entity sends an ADD operation command to the TC MRFP network element again, indicates the TC MRFP network element to ADD another RTP in the context where the RTP1_ TC is located, the media coding format in the opposite-end media description information is the media coding format recorded on the media template of the called B, and the TC MRFP network element replies that the TC-AS establishes the RTP successfully. For convenience of description, this RTP is referred to as RTP2_ TC.

4) and the TC-AS sends the updated media description information and the call progress message to an AS management entity together to inform the AS management entity that the execution of the service logic of the LI-AS is completed.

5) the AS management entity replaces the media description information of the calling party with the media description information of RTP2_ TC, wherein the media coding format of the calling party is modified into codec-A and media coding format codec-B recorded on the media template of the called party B.

through the above operation, the TC-AS indicates that the media resource required for TransCoding is created on the TC MRFP. The TC-AS sends back the modified call related information, in particular the media description information of the caller, to the AS management entity. The AS management entity replaces the media description information of the calling side with the media description information of RTP2_ TC.

Step S810, the AS management entity completes the static trigger of AS sequence, and returns the call request message to the S-CSCF, and continues to manage the sending and transferring of the subsequent call message. After the LI-AS and TC-AS triggers are complete, the RTP2_ LI in the LI MRFP establishes a connection with the RTP1_ TC in the TC MRFP. The AS management entity loops the service request message back to the S-CSCF after being coded by the SIP subsystem of the protocol adaptation layer entity, and the message contains media description information of which the media description information of the calling side is RTP2_ TC.

the above steps S801 to S810 are processing flows of static triggering of the AS sequence completed by the AS management entity when the calling-side non-multiparty call service is triggered.

The following steps S811-814 are the processing flow of static triggering of the AS sequence completed by the AS management entity when the calling side multi-party call service is performed. When the steps S815-820 are called side triggering, the AS management entity completes the processing flow of static triggering of the AS sequence, which is similar to the processing flow of non-multiparty call service triggering of the calling side, and the following are introduced respectively:

step S811, the AS management entity determines that the service user is monitored, and adds LI-AS to the AS sequence to be triggered, AS in step S804.

In step S812, the AS management entity determines that the AS sequences to be statically triggered are LI-AS and O-AS in sequence.

The multi-party call service needs to be triggered to a conference media gateway in advance to prepare conference media resources, and the codecs supported by the conference media gateway are rich enough, so that an AS (application server) is not needed to perform TransCoding operation on a calling party and a called party; meanwhile, for monitoring the multi-party call service, AS long AS the chairman user of the conference is monitored, all users can be monitored, so that LI-AS needs to be triggered first, and then O-AS needs to be triggered, that is, the triggering sequence of the AS is: LI-AS, O-AS.

step S813, the AS management entity triggers LI-AS, and the LI-AS notifies the AS management entity after executing the service logic. The same as step S808.

step S814, the AS management entity triggers the O-AS, and the O-AS notifies the AS management entity after executing the service logic.

the step is similar to the step S807, specifically, an O-AS related data area is created for the AS management entity, the call related information is sent to the O-AS, after the O-AS executes the multi-party call service, the AS management entity is notified that the O-AS has been triggered, and the modified call related information is sent back to the AS management entity.

The above steps S811-814 are the processing flow of static triggering of the AS sequence completed by the AS management entity when the calling side multi-party call service.

when the following steps S815-820 are called side triggering, the AS management entity completes the processing flow of static triggering of the AS sequence, which is introduced AS follows:

In step S815, the AS management entity determines that the codec supported by the calling and called parties is different. In the decision logic of step S802, if mode ═ MT indicates that the present trigger is MT phase trigger, i.e. called side trigger, then the role of AS at this time is T-AS, which is used to execute the called side service of the service user. The priority order of the judging logic of the AS management entity for executing the LI-AS and TC-AS triggering or not when the calling side triggers and the called side triggers is different. In this step, it is necessary to first determine whether the codec supported by the calling party and the called party is the same.

Similar to step S805, when the AS management entity performs a number conversion on the called party, the AS management entity compares the media coding capability of the calling party carried in the call message with the called media coding capability in the called media capability template in the called party number segment configuration, if there is no intersection, it indicates that the calling and called codecs are different, and needs to trigger the TC-AS, so AS to perform media coding-decoding conversion using the TC MRFP. Different from step S805, this step may also obtain the media codec capability of the called user by querying the user attribute of the called user. In the step, the encoding and decoding of the calling party and the called party are different, and the TC-AS needs to be triggered, so that the TC-AS is added into an AS sequence to be triggered.

Step S816, the AS management entity determines that the called user is monitored. The method is similar to step S804, except that it is determined whether the called user is monitored. In this step, the called user is monitored and needs to trigger the LI-AS, so the LI-AS is added to the AS sequence to be triggered.

And step S817, the AS management entity determines that the AS sequences to be statically triggered are TC-AS, LI-AS and T-AS in sequence.

After judging that the trigger is called side trigger, the AS management entity determines that the AS sequences to be statically triggered are TC-AS, LI-AS and T-AS in sequence. The advantage of this static trigger sequence is:

1) this sequence facilitates the monitoring of call forwarding class services. Supposing that the called service user B registers the unconditional forwarding service, forwarding to the user C; user B has been announced by the LEA as a listening user. After a call request of a user A calling a user B is sent to an AS, if the T-AS is triggered first, the T-AS updates a called user to a user C after judging that the user B has an unconditional forwarding service, and stores the user B AS an original called number, and then the LI-AS is triggered, and the LI-AS cannot judge that the user B is monitored according to the called number. Therefore, before triggering the T-AS, the LI-AS is triggered first, the LI-AS completes the monitoring service logic of the called user B first, and then the LI-AS triggers the T-AS, and the T-AS completes the forwarding service.

2) and reducing invalid triggers to the T-AS. When the called side is triggered, the media coding and decoding capability of the called user can be obtained through called number analysis and user attribute inquiry of the called user, so that whether the coding and decoding of the calling and the called are the same or not can be accurately judged. The call may be terminated based on the switch configuration decision after a TC-AS trigger failure or a TC-AS indicating a TC MRFP media preparation failure. In this scenario of terminating a call, if the T-AS triggers before the TC-AS, the business logic done by the T-AS is meaningless and belongs to an invalid trigger. To reduce such invalid triggering of the T-AS, the T-AS must be ranked behind the TC-AS, and depending on the execution result of the TC-AS, it is decided whether to actually trigger the T-AS.

3) similar to the triggering of the calling side after the LI-AS is close to the O-AS, the triggering of the T-AS after the LI-AS is close to the LI-AS also facilitates the reporting of the monitored communication events in the value added service implementation process.

Step S818, the AS management entity triggers TC-AS, and the TC-AS notifies the AS management entity after executing the service logic. The processing procedure of this step is similar to step S809.

step S819, the AS management entity triggers LI-AS, and the LI-AS notifies the AS management entity after executing the service logic. The processing procedure at this step is similar to step S808.

Step S820, the AS management entity triggers T-AS, and the T-AS notifies the AS management entity after executing the service logic.

The method specifically comprises the steps that a T-AS related data area is created for an AS management entity, call related information is sent to the T-AS, after the T-AS executes a called service sequence of a called service user, the AS management entity AS is informed that the T-AS is triggered, and the modified call related information is sent back to the AS management entity. The called service sequence of the called service user may have: forwarding class (unconditional forwarding, busy forwarding, no answer forwarding, etc.), number display class (calling number display, etc.), authority class, called one-number-call, color ring, no-disturbance, call waiting, call hold service, etc.

The procedure of the T-AS executing the called side service (taking unconditional forwarding service AS an example):

1) The T-AS searches the service attribute of the called user B, finds that the called user B registers the unconditional forwarding service and obtains the unconditional forwarding number C of the called user.

2) the T-AS uses the message of the internal format to initiate a new call request to the SIP subsystem of the protocol adaptation layer entity, the calling number B and the called number C in the new call request message are carried with forwarding information.

3) The SIP subsystem of the protocol adaptation layer entity sends an INVITE message to the C user and reports the call state and the call information of the C user to the T-AS.

4) the T-AS passes the call state and call information of the new call to the original caller a.

5) And after the T-AS finishes the called service, sending a call progress message to an AS management entity.

the above steps S815-820 describe the processing flow of the AS management entity completing the static trigger of the AS sequence when the called side triggers.

EXAMPLE six

Fig. 9 is a flowchart of a method for implementing lawful interception in an IMS network according to a sixth embodiment of the present invention, and AS shown in fig. 9, this embodiment provides a whole flow in which an AS management entity manages the transmission and sending of subsequent call messages such AS ringing and answering after a call request message, updates the codec conversion media on the TC MRFP and the peer media description information of the monitored media on the LI MRFP, respectively, completes the media request and answer balance on each network element in the whole call process, so that a calling party and a called party can establish a call after passing through TransCoding, and the call can be normally intercepted. The method specifically comprises the following steps:

in step S901, the AS management entity receives a call response message sent by the S-CSCF, where the message carries media description information SDP _ B of the called user B.

After the AS management entity completes the static triggering of the AS sequences O-AS, LI-AS and TC-AS, the service request INVITE message is encoded by a protocol adaptation layer entity SIP subsystem and then looped back to the S-CSCF, and the message contains media description information of which the media description information of the calling side is RTP2_ TC.

The S-CSCF routes the call request to the called side network to call the called user B, B rings and answers, and the answer message carries the media description information SDP _ B of the called user B, wherein the coding and decoding format is codec-B. The S-CSCF sends the response message to the AS, and the response message is decoded by the protocol adaptation layer entity and then is transmitted to the AS management entity.

In step S902, the AS management entity sends the response message and the related media description information to the TC-AS. And the TC-AS indicates the TC MRFP network element to modify the opposite-end media description information of the RTP2_ TC into the media description information SDP _ B of the called user B.

According to the principle of the reverse serial sending of the response message, the AS management entity sends the response message and the related media description information to TC-AS, wherein the media description information of the called side is the media description information SDP _ B of the called user B. And the H.248 subsystem of the TC-AS control protocol adaptation layer entity sends a Modify operation command to the TC MRFP network element, and modifies opposite-end media description information of the RTP2_ TC into media description information SDP _ B of the called user B. And after the TC MRFP network element replies that the TC-AS is successfully modified, the TC-AS sends the updated media description information and the call progress message to the AS management entity together, and informs the AS management entity that the TC-AS finishes processing the response message. The AS management entity updates the called side media information to RTP1_ TC.

in step S903, the AS management entity sends the response message and the related media description information to the LI-AS. And the LI-AS indicates the LI MRFP network element to modify the opposite-end media description information of the RTP2_ LI into the media description information RTP1_ TC of the called side.

The AS management entity sends a response message and the related media description information to the LI-AS, where the called side media information has been updated to RTP1_ TC. And the H.248 subsystem of the LI-AS control protocol adaptation layer entity sends a Modify operation command to the LI MRFP network element, and modifies opposite-end media description information of the RTP2_ LI into media description information RTP1_ TC of the called side. And after the LIMRFP network element replies that the LI-AS is successfully modified, the LI-AS sends the updated media description information and the call progress message to the AS management entity together, and informs the AS management entity that the LI-AS finishes the processing of the response message. The AS management entity updates the called side media information to RTP1_ LI.

in step S904, the AS management entity sends the response message and the related media description information to the O-AS. And the O-AS completes the processing of the service logic.

Step S905, the AS management entity returns the response message to the S-CSCF, the media description information carried in the message is the media description information of RTP1_ LI, and the S-CSCF sends the response message to the calling user A through the P-CSCF.

Therefore, the media request and response balance on each network element in the whole calling process is completed, the calling and called parties establish a call after transmission, and the call can be normally monitored by the LEA. Fig. 10 is a schematic diagram of media connection for implementing a lawful interception method in an IMS network according to a sixth embodiment of the present invention, as shown in fig. 10, a connection is established between the media of calling party a and an intercepted media RTP1_ LI on limrpp; the listening media RTP1_ LI is interworked with the listening media RTP2_ LI; monitoring a media RTP2_ LI and a codec conversion media RTP1_ TC on a codec conversion resource processor; the coding and decoding conversion media RTP1_ TC and the coding and decoding conversion media RTP2_ TC are intercommunicated after coding and decoding conversion; the codec converted media RTP2_ TC establishes a connection with the media of the called subscriber B. Therefore, after media of the calling and called users pass through the monitoring resource media processor and the coding and decoding conversion resource processor, connection is established, and conversation can be established. And the monitoring media RTP1_ LI and RTP2_ LI on the LI MRFP copy a piece of media respectively and send the copy to the monitoring function submitting gateway, thereby realizing the monitoring of the media of the calling and talking parties.

EXAMPLE seven

Fig. 11 is a flowchart of a method for implementing lawful interception in an IMS network according to a seventh embodiment of the present invention, and AS shown in fig. 11, this embodiment provides how an AS management entity dynamically triggers a TC-AS to implement TransCoding after a media negotiation failure, and particularly provides a process how to implement TransCoding after a media negotiation failure when a calling user or a called user is intercepted, that is, to implement interception of a TransCoding call scenario after a media negotiation failure. The method specifically comprises the following steps:

Step S1101, the AS management entity receives a call request message initiated by the S-CSCF, and the media description information carried in the request message is the media description information of the calling party a. The process of the AS management entity completing the static triggering of the AS sequence can refer to steps S801-810 of the fifth embodiment. In step S805, the AS management entity does not determine that the codec supported by the called party is different from the calling party, and the reason for the non-determination may be that the called media capability template is not configured, or the called media codec capability in the called media capability template intersects with the calling media codec capability, so the AS management entity does not add the TC-AS to the AS sequence to be triggered. The AS sequence triggered by the AS management entity is AS follows: O-AS, LI-AS. After the LI-AS executes the monitoring service logic, the media description information is updated. The AS management entity replaces the media description information of the calling side with the media description information of RTP2_ LI.

Step S1102, the AS loops back the service request INVITE message to the S-CSCF, where the message includes media description information of the calling party. And the S-CSCF routes the call request to the called side network to call the called party. The called user does not support the media coding and decoding format of the calling user, sends 488 or 606 failure response message, and carries the media description information of the called user B, including the supported media coding and decoding format codec-B.

In step S1103, after receiving the internal release message decoded and converted by the protocol adaptation layer from the 488 or 606 failure response message, the AS management entity analyzes and determines that the reason for the call failure is caused by the difference between the codec capabilities of the calling party and the called party, so AS to intercept the release message, trigger the TC-AS, and start the timer to wait for the TC-AS to execute the TC service logic.

In step S1104, the AS management entity triggers the TC-AS. The same AS step S809, the AS management entity creates a TC-AS related data area, sends the call related information to the TC-AS, and the TC-AS instructs the TC MRFP to prepare a TransCoding media resource, notifies the AS management entity that the TC-AS has been triggered after the completion of the execution, and returns the modified call related information, especially the media description information of the calling side, to the AS management entity.

In step S1105, the AS management entity replaces the media description information of the calling side with the media description information of RTP2_ TC. At the same time, adding TC-AS to the triggered AS sequence and reordering. Thus, the response message in the subsequent call process passes through the TC-AS.

Step S1106, the AS management entity sends a new call request message to the S-CSCF, where the message carries new media description information of the calling party, that is, after the TransCoding operation, and the media coding format in the media description information and the media coding format of the called party have intersection, that is, the calling party and the called party can perform normal call.

The above steps describe how to implement the TransCoding procedure after codec negotiation fails in the case that the calling subscriber is monitored. The process also has the following scenario changes, which can be handled similarly:

1) The calling is defined by different sequence of the network elements, the network element before the network element is called a forward network element (forward for short), and the network element after the network element is called a backward network element (backward for short). The flow in fig. 11 is a TC-AS dynamically triggered upon receipt of a 488 or 606 response message to the INVITE request message. If a 488 or 606 response message to the media negotiation UPDATE request message is received during the call, the same dynamic trigger TC-AS process is performed with reference to fig. 9. Both of these cases are 488 or 606 response messages back, and after the triggering is completed, the AS management entity adds the TC-AS to the last end of the triggered AS sequence. In this way, the subsequent response message also passes through the TC-AS first, so that the triggered AS can not sense and trigger the TC-AS backwards, and the influence on the triggered AS is avoided.

2) If in the calling process, the 488 or 606 response message of the forward media negotiation UPDATE request message is received, the same dynamic trigger TC-AS processing is also carried out, and the difference is that after the trigger is completed, the AS management entity adds the TC-AS to the foremost end of the triggered AS sequence. Namely, the triggered AS can not sense that the TC-AS is triggered in the forward direction, and the influence on the triggered AS is avoided.

3) On the called side, the called user is monitored, and if a 488 or 606 response message of the INVITE request or the UPDATE request is received in the forward direction or the backward direction, the same dynamic trigger TC-AS processing is performed with reference to fig. 9.

4) If the called user B does not carry the media codec format supported by itself in the 488 or 606 message, the TC-AS indicates that the media codec format in the media description information prepared by the TC MRFP is all the codec formats supported by the TC MRFP, and the new call request message carries the media description information.

Example eight

fig. 12 is a flowchart of a method for implementing lawful interception in an IMS network according to an eighth embodiment of the present invention, and AS shown in fig. 12, this embodiment provides how an AS management entity dynamically triggers an LI-AS, so AS to implement interception in a scenario where a calling side call is abnormally played, which is an improvement on a static interception triggering and management mechanism of the AS management entity.

according to the basic scheme of the static trigger of the AS management entity described in the fifth embodiment, when the calling side is triggered by the non-multiparty call service, the LI-AS is located behind the O-AS, and if abnormal sound reproduction is performed on the calling user by the O-AS at the moment, because the LI-AS is not triggered yet, no connection is established between the sound reproduction media resource gateway and the LI MRFP, the LI-AS cannot monitor the sound reproduction. To solve this problem, the AS management entity may perform optimization by using the following embodiment to dynamically trigger LI-AS. The method specifically comprises the following steps:

Step S1201, the same AS steps S801-S806, the AS management entity receives the call request message, judges that the trigger request of the S-CSCF is the calling side and is the non-multiparty call service trigger, and determines that the AS sequence to be statically triggered is O-AS, LI-AS and TC-AS in sequence;

Step S1202, the AS management entity triggers the O-AS, and finds out that abnormal sound reproduction needs to be carried out on the calling user when the O-AS executes the service logic, such AS user arrearage shutdown or call limit service, and service prompt sound of response needs to be reproduced for the user. The O-AS first instructs the MRFP to prepare the media for playback: the h.248 subsystem of the control protocol adaptation layer entity sends an ADD operation command to the MRFP network element to instruct the MRFP network element to ADD an RTP, the opposite-end media description information of the MRFP network element points to the media description information SDP _ a of the calling subscriber a, the MRFP replies to the O-AS that the RTP is successfully created, and for convenience of description, the system is referred to AS RTP _ MRFP in this example. At this moment, because the playback needs to be monitored, the O-AS does not continue to complete the media negotiation process of the calling party a and the abnormal playback media, but notifies the AS management entity of the call progress message and the media description information of the abnormal playback media RTP _ MRFP, so that the AS management entity dynamically triggers the LI-AS to monitor the playback.

In step S1203, the AS management entity determines that the calling subscriber a is monitored. The method is the same as step S804.

Step S1204, AS management entity creates LI-AS related data area, sends call related information to LI-AS, including media description information of media RTP _ MRFP played abnormally. The LI-AS performs the listening service logic in the same way AS step S808. The listening media created by LI MRFP are: RTP1_ LI and RTP2_ LI, wherein the peer media description information of RTP1_ LI points to the media description information of the abnormal playback media RTP _ MRFP. The LI-AS informs the AS management entity that the LI-AS has completed triggering and sends the media description information of the LI MRFP to the AS management entity.

Step S1205, the AS management entity sends the media description information of the monitored media to the O-AS. The O-AS instructs the MRFP to modify the peer media description information of the RTP _ MRFP to be the media description information of the RTP1_ LI. Thus, the media negotiation of the monitoring media and the abnormal playback media is completed. And after the execution is finished, the O-AS informs the AS management entity.

in step S1206, the AS management entity sends the media description information of the calling subscriber a to the LI-AS, and the LI-AS controls to modify the opposite-end media description information of the RTP2_ LI to be the media description information of the calling subscriber a. After the execution is completed, the LI-AS informs the AS management entity.

step S1207, the AS management entity notifies the SIP subsystem of the protocol adaptation layer entity, and uses 183 message to carry the media description information of RTP2_ LI to play back to the calling party a.

Through the steps, the AS management entity dynamically triggers the LI-AS, completes the media negotiation between the abnormal playback media on the MRFP and the monitoring media on the LI MRFP together with the O-AS executing the service logic, so that the voice packet on the MRFP flows to the LI MRFP, and then completes the media negotiation between the monitoring media on the LI MRFP and the calling party, so that the voice packet on the LI MRFP flows to the calling party, thereby monitoring the abnormal playback.

Fig. 13 is a schematic diagram of media connection for implementing a lawful interception method in an IMS network according to an eighth embodiment of the present invention, and as shown in fig. 13, a media RTP _ MRFP on an abnormal playback media resource processor is connected to an interception media RTP1_ LI on an LI MRFP; the listening media RTP1_ LI is interworked with the listening media RTP2_ LI; listening for media RTP2_ LI establishes a connection with the media of calling party a. Therefore, the abnormal playback media are forwarded by the monitoring resource media processor and then connected with the media of the calling user A, and the calling user A can hear the abnormal playback. And the monitoring media RTP1_ LI and RTP2_ LI on the LI MRFP copy a piece of media respectively and send the media to the monitoring function submission gateway, thereby realizing the monitoring of the abnormal playback media.

in the embodiment of the present invention, the multimedia Resource function Controller MRFC (MRFC for short) function is integrated with each AS, that is, the O-AS or the T-AS, LI-AS, and TC-AS may be used AS MRFC to control respective multimedia Resource processors (MRFP for short). For convenience of description, the MFRP is called a media resource handler of a corresponding function according to functions and roles: a coding/decoding conversion media resource processor (TC MRFP), a monitoring media resource processor (LI MRFP) and an abnormal playback media resource processor.

as can be seen from the above description, the technical solution for implementing lawful interception in an IMS network provided by the present invention is roughly as follows:

From receiving a call request message which is initiated from an S-CSCF and decoded and adapted by a protocol adaptation entity, an AS management entity judges and analyzes according to information such AS the indication of an MO or an MT, whether a multi-party call service is available, whether monitoring is needed, whether pre-coding and decoding conversion is needed and the like, and determines an AS sequence to be statically triggered;

Then the AS management entity triggers the AS in the AS sequence in sequence to complete the preparation of monitoring media and encoding and decoding conversion media. When a certain AS is triggered, the related information of the call is sent to the AS, the AS executes respective service logic to modify the related information of the call and then sends the modified information back to the AS management entity, and the AS management entity updates and stores the information. After the AS in the AS triggering sequence is completely triggered, the call request message is looped back to the S-CSCF, and the call is continued;

then AS management entity manages the transmission and transmission of ringing, answering and other follow-up calling messages after calling request message, completes the media negotiation between calling and called media, monitoring media and codec conversion media, makes calling and called establish conversation after codec conversion, and the conversation can be monitored

finally, the AS management entity dynamically triggers LI-AS according to a special scene in the calling process or dynamically triggers TC-AS according to the received abnormal response message, adds the dynamically triggered AS into the triggered AS sequence and reorders the sequence; and managing the transmission and sending sequence of the subsequent messages to complete the whole call.

Through the steps, the legal monitoring in two calling scenes of TransCoding after the pre-TransCoding and the media negotiation failure is realized under the effective management of the AS management entity to the O-AS or the static and dynamic triggering modes of the T-AS, the LI-AS and the TC-AS, and the monitoring range of the legal monitoring is enlarged.

based on the technical scheme, the invention achieves the following technical effects:

although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, and the scope of the invention should not be limited to the embodiments described above.

Claims

1. A method for realizing lawful interception in a multimedia subsystem IMS network is applied to an Application Server (AS) management entity, and the method comprises the following steps:

After receiving a call request message initiated by a service-call session function entity (S-CSCF), determining an AS sequence to be triggered based on a preset condition;

Converting the call request message into an internal call request message, sequentially triggering each AS in the AS sequence to be triggered, sequentially sending the internal call request message to each AS, and receiving an internal call request response message returned by each AS after each AS is triggered; then converting the received internal call request response message returned by the last AS into a call request response message, and sending the call request response message to the S-CSCF;

And managing the transmission and sending of subsequent call messages after the call request response message is carried out, and establishing normal conversation after the calling side and the called side are converted through coding and decoding through media negotiation, wherein the conversation is monitored.

2. the method of claim 1, wherein managing the calling and called sides to establish normal conversation after codec conversion through media negotiation comprises:

And finishing the media negotiation among the calling and called media, the monitoring media and the coding and decoding conversion media, so that the calling and called users establish normal conversation after coding and decoding conversion.

3. The method of claim 1, wherein the preset conditions include:

Whether the call request message carries an originating MO indication or a terminating MT indication,

Whether the calling subscriber is a multi-party call service,

Whether the calling subscriber or the called subscriber is monitored, or,

Whether pre-coding and decoding conversion is carried out is determined by judging whether the media coding and decoding of the called user and the calling user have intersection.

4. The method AS claimed in claim 3, wherein determining a to-be-triggered AS sequence based on a preset condition comprises:

If the call request message carries MO indication, adding a calling application server O-AS into the AS sequence to be triggered, and if the call request message carries MT indication, adding a called application server T-AS into the AS sequence to be triggered;

If the calling user is a multi-party call service, not adding the AS into the AS sequence to be triggered, and if the calling user is a non-multi-party call service, adding the AS into the AS sequence to be triggered;

determining whether to trigger and monitor an application server LI-AS based on whether a calling user or a called user is monitored, if so, adding the LI-AS into the AS sequence to be triggered, and if not, not adding the LI-AS into the AS sequence to be triggered;

5. the method of claim 4, wherein the determination of whether to perform pre-codec conversion is made by:

And judging whether the pre-coding and decoding conversion is needed or not according to the media template of the attribute of the service user recorded in the inquired database or the media template of the called user number segment recorded in the number analysis.

6. The method of claim 1, wherein after the calling and called sides are converted by codec to establish a normal call, the method further comprises:

Under an abnormal call scene, dynamically triggering LI-AS or TC-AS;

Adding the dynamically triggered AS into the triggered AS sequence and reordering;

And managing the transmission and sending sequence of the subsequent messages to complete the whole call.

7. the method of claim 6, wherein dynamically triggering LI-AS or TC-AS in abnormal call scenarios comprises:

Dynamically triggering LI-AS according to a special scene in the calling process or dynamically triggering TC-AS according to the received abnormal response message; the special scene is a scene when the normal call is abnormal.

8. The method of claim 1, wherein the call request message received is: a call request message initiated by said S-CSCF and decoded and adapted by a protocol adaptation entity.

9. A device for realizing lawful interception in a multimedia subsystem IMS network is applied to an application server AS management entity, and is characterized in that the device comprises:

The system comprises a sequence establishing module, a sequence determining module and a triggering module, wherein the sequence establishing module is used for determining an AS sequence to be triggered based on a preset condition after receiving a call request message initiated by a service-call session function entity (S-CSCF);

The static trigger module is used for converting the call request message into an internal call request message, sequentially triggering each AS in the AS sequence to be triggered, sequentially sending the internal call request message to each AS, and receiving an internal call request response message returned by each AS after the triggering of each AS is completed; then converting the received internal call request response message returned by the last AS into a call request response message, and sending the call request response message to the S-CSCF;

And the call establishing module is used for transmitting and sending subsequent call messages after the call request response message, establishing normal call after the calling side and the called side are converted through coding and decoding through media negotiation, and monitoring the call.

10. the apparatus of claim 9, wherein the preset conditions include:

whether the calling subscriber is a multi-party call service,

whether the calling subscriber or the called subscriber is monitored, or,

11. The apparatus AS claimed in claim 10, wherein the sequence establishing module determines a to-be-triggered AS sequence based on a preset condition, including:

12. the apparatus of claim 9, wherein the apparatus further comprises:

the dynamic triggering module is used for dynamically triggering LI-AS or TC-AS by the AS management entity under an abnormal call scene; adding the dynamically triggered AS into the triggered AS sequence and reordering; and managing the transmission and sending sequence of the subsequent messages to complete the whole call.

13. The apparatus of claim 12,

The dynamic trigger module is also used for dynamically triggering LI-AS according to a special scene in the calling process or dynamically triggering TC-AS according to the received abnormal response message; the special scene is a scene when the normal call is abnormal.

14. An application server in an IMS network, the application server comprising: AS management entity, protocol adaptation entity, and logically mutually independent service application server O-AS or T-AS, monitoring application server LI-AS, and codec conversion application server TC-AS, wherein,

the AS management entity is used for triggering logically related and independent O-AS, T-AS, LI-AS and/or TC-AS according to the static trigger and dynamic trigger management mechanism; storing and managing the relevant information of the whole call; managing the sending and delivery of call messages;

The protocol adaptation entity comprises an SIP protocol subsystem and an H.248 protocol subsystem and is used for decoding messages of other network elements received by the application server, converting the messages into internal messages and sending the internal messages to the AS management entity;

the O-AS and the T-AS are used for executing the value-added service logic of the calling side or the called side of the service user;

The LI-AS is used for executing monitored service logic;

The TC-AS is used for executing the business logic of coding and decoding conversion, controlling a coding and decoding conversion media resource processor to prepare a coding and decoding conversion media and negotiating the media of a calling party and a called party;

The static trigger comprises:

the dynamic triggering comprises: