MXPA00012965A - Signalling in a telecommunications network - Google Patents

Abstract

A method of transmitting calling user addressing information in a telecommunications network using Signalling System No.7. A call set-up phase is conducted between two exchanges of the telecommunication network to reserve a channel for user data. During this set-up phase, an Initial Address Message is transmitted from the first exchange to the second exchange, the Initial Address Message containing an Application Transfer Mechanism indicator to notify the second exchange that addressing information will be transmitted in one or more subsequent Application Transfer Mechanism Messages. The said one or more Application Transfer Mechanism Messages are then transmitted from the first node to the second node, each message including a Unidirectional flag to indicate that the message relates to the basic call context application and not peer-to-peer association context.

Description

ALIZATION IN A TELECOMMUNICATIONS NETWORK Field of the Invention The present invention relates to signaling in a telecommunications network and more particularly, although not necessarily to the transmission of information in relation to the address of user or users of origin over the network.

BACKGROUND OF THE INVENTION The public telephone networks are increasingly making use of a signaling protocol known as Signaling System No. 7 (SS7) to control the networks and transport the data necessary for call establishment and control. The transmissions in such networks, both user data and signaling, are physically transported by a Time Division Multiple Access (TDMA) transmission protocol operating in a given frequency band. For example, in Europe, the transmission protocol E.1 is used, whereas in the United States protocol T.1 is used (the main difference between these two protocols, which is the number of time segments per TDMA structure). SS7 is usually referred to as a common channel signaling system because the signaling data packets are transported on a common channel constructed from a time segment per TDMA structure. A node in the network (for example, a transit exchange) determines whether a signaling message is for it or not or determines whether the message should be routed to another node, based on a destination point code address transported with the message. Figure 1 illustrates the functional architecture of a network node SS7. The lowermost layer of SS7 is the Message Transfer Part (MTP) that provides the SS7 message segment for incorporation into the slot allocated in the TDMA structure. The MTP responsible for the reliable transfer of messages on behalf of certain User Parties through the SS7 network regardless of possible network failures (for example, using error verification, correction, forwarding, etc.). The User Parties make use of the MTP that includes a Telephone User Part (TUP), the Signaling Connection Control Part (SCCP), the Transaction Capability Application Part (TCAP), and the User Part of ISDN Signaling (ISUP). The TUP, TCAP, and ISUP respectively handle the signaling associated with service applications not related to the call, an Integrated Digital Services (ISDN) service network application, and a Basic Telephone Service (POTS) application. The TUP, SCCP, and TCAP are not of any particular relevance here and for further information the reader should refer to the relevant standards (ITU-T Q.700 recommendation series). The following discussion is mainly related to the ISUP. The Integrated Digital Services Network (ISDN) is finding widespread use in the transmission of all types of data (for example, telephony, faxcimil, telex) using a common digital format. In its broader implementation, ISDN provides the end-to-end transmission of digital data in a common format, that is, from a user's home phone to the telephone of a destination user. In a lesser sense, the ISDN may provide communication between the exchanges of a telecommunications network so long as, for example, one or both of the originating and destination user communicates with its associated local exchange using an analogous format. One of the functions of the ISUP within the ISDN is to assist in the establishment of an end-to-end connection between the originating user's phone and the destination user's telephone. In particular this involves reserving, during a call setup phase, a user data channel between the local exchanges of the originating user and the destination user (if the exchanges are different). For this purpose, the ISUP makes use of the Initial Address Message (lAM) capable of transporting 252 octets of data and that can be transmitted (by means of the lAM) in one of the E.1 // T.1 TDMA segments assigned to the SS7 network (one LAM per call). The information carried by the LAM is of many different parameters and indicators, including the number of the calling user and possibly a destination / redirection number. The structure of the lAM message is defined in ITU-T Recommendation Q.763. It is currently proposed to introduce new services in stable telecommunication networks such as number portable capacity, personal monodirectional telecommunication, intelligent network services and presentation of identification of the name of origin. The identity information of the existing source user (moved by the lAM) will not serve the purpose of the existing value-added services or service applications (eg, emergency services, malicious call identification) in addition to those new services proposed (in particular due to the portable capacity of the number that will result in the loss of the geographic importance of a caller number). In order to support the proposed new services it will be necessary to improve the originating user address information transmitted in the calling establishment phase of a call, the improvement is distinguished by the separation of the logical and physical address information of a user from origin. For example: 1. the geographic location (ie latitude, longitude and altitude) of the originating user; 2. The logical source user ID (for example, directory number, UPT number, IN service number); 3. The logical subscriber ID (that is, the identity of the owner of the subscription that does not have to be the real originating user (for example, when the user of logical origin is the identity of an employee and the logical subscriber identification) is the company that receives the invoice) 4. The user ID of physical origin (ie an identity related to the physical / geographical connection of the originating user for the service telecommunications network) 5. The name of the user of origin (that is, a text link that corresponds to the name of the originating user; and 6. Additional origin user information (that is, information received from the user) The above identities can be transmitted from the caller's local exchange to the the destination user, or to an intermediate node, in the case of a call diversion, the identities referred to in articles 1 to 5 will be repeated in a call, ie the leader of the user of origin n real and the new user of origin (that is, the subscriber originally called) in a transferred call. According to the list of source user information becomes more extensive, sending it through dedicated parameters within the lAM, in addition to the mandatory or essential call establishment data, may not be possible in all cases.

An alternative approach is to send the data using the SCCP signaling capability that provides an end-to-end association. However, this represents an obstacle to the importation of other services (for example the source-dependent route) that operate in an intermediate node. Under the existing ISUP specification, there is the possibility of sending a "segmentation" message (SGM), after a message lAM that provides the SGM is indicated in the lAM. The SGM is also 252 octets in length and allows additional information to be transmitted. Therefore, it is possible to include additional user address information in the SGM. However, in many cases, the extra 252 octets may not be enough.

Brief Description of the Present Invention It is an object of the present invention to overcome or at least mitigate the aforementioned disadvantages of the existing SS7 based telecommunications networks. In particular, it is an object of the present invention to provide an increased ability to transmit originating user address information during a call setup phase. According to a first aspect of the invention, there is provided a method for transmitting the originating user address information in a telecommunications network using Signaling System No. 7, the method comprising conducting a call set-up phase. between two nodes of the telecommunications network for reserving a channel for user data, the set-up phase comprising: transmitting an initial address message from the first node to a subsequent node, the Initial Address Message containing a Mechanism indicator of Application Transfer to notify the subsequent node that the address information will be transmitted in one or more subsequent Application Transfer Mechanism Messages; and transmit said Messages of the Mechanism of Application transfer from the first node to the subsequent node. The embodiments of the present invention allow a substantially unlimited amount of address information to be transmitted using the Messages of the Application Transfer Mechanism. Preferably, the Initial Address Message contains a limited amount of address information of the originating user, for example, the telephone number of the originating user. Preferably, the Initial Address Message and the Application Transfer Mechanism Message (s) each contain an Application Transport Parameter (APP) that translates the address information. More preferably, each APP contains an indicator (for example, a Monodirectional Indicator), the purpose of which is to indicate to a receiving node whether the APP belongs or not to a direct connection communication or to any application that may be present in the receiving node. Preferably, the originating user address information transmitted in said one or more Application Transfer Mechanism Messages includes at least one of: the geographical location of the originating user; the user ID of the logical source; the logical subscriber ID; the user ID of physical origin; the name of the originating user; and the corresponding derivation user identities. Preferably, the Initial Address Message and its application transfer mechanism messages are transmitted over the telecommunications network in respective individual data packets, i.e. respective Time Division Multiple Access Time (TDMA) segments. Most preferably, the last message of the transmitted application transfer mechanism contains an indicator set to indicate to the receiving node that the message is the last Message of the Application Transfer Mechanism. According to a second aspect of the present invention, the apparatus for transmitting originating user address information in a telecommunications network using Signaling System No. 7 is provided, wherein a call establishment phase is conducted between two telecommunication network nodes for reserving a channel for user data, the apparatus comprising: first processing means provided in the first node and placed to generate an Initial Address Message and to transmit this message from the first node to the subsequent node , the Initial Address Message containing an indicator of the Application Transfer Mechanism to notify the subsequent node that the address information will be transmitted in one or more subsequent Application Transfer Mechanism Messages; and second processing means placed to generate said one or more Application Transfer Mechanism Messages and to transmit the Messages from the first node to the subsequent node. Preferably, the first and second processing means are provided with a suitably programmed computing system. According to a third aspect of the present invention, a method is provided for transmitting information in a telecommunications network, using Signaling System No, 7, during a call set-up phase between two nodes of the network, the information that is transmitted in a monodirectional form from a first of the nodes to the subsequent node and is intended for an application present in the subsequent node, the method comprising: transmitting an Initial Address Message from the first node to the subsequent node, the Address Message Initial that contains an indicator of the Application Transfer Mechanism to notify the subsequent node that said information will be transmitted in one or more subsequent Application Transfer Mechanism Messages; and transmitting said Application Transfer Mechanism Messages from the first node to the subsequent node, the method further comprises including in the or in each message of the Application Transfer Mechanism an indicator to indicate to a receiving node whether or not the message is a monodirectional message. The subsequent node may be an intermediate node in the transmission path of said information, the method comprising trusting the Application Transfer Message Mechanisms received to a subsequent node in an unaltered state when the messages contain a monodirectional indicator that is not present. settled down.

Brief Description of the Drawings for a better understanding of the p.ui and in order to show how it can be carried out, reference will now be made, by way of example, to the drawings that accompany it, in which: Figure 1 illustrates the functionality of the architecture of a conventional node of Signaling System No. 7; Figure 2 illustrates the functionality of the architecture of a modified Signaling System No. 7 network; Figure 3a is a flow chart illustrating the reception of the lAM and APM messages in a central office of the system of Figure 2; and Figure 3b is a flowchart showing the illustration of the process of assembly message segments in a central office of the system of Figure 2.

Detailed Description of Certain Modalities. The disadvantages of the existing ISUP with respect to transporting the originating user address information has been described above. It is proposed here to overcome these disadvantages by making use of the new transport mechanism which has been recently defined for ISUP. This new transport mechanism is known as the Application Transport Mechanism (APM) and has been specified (ITU Recommendation Q.765 document) in order to allow ISUP to provide the same capabilities as the Transaction Capability Implementation Part. In particular, APM allows ISUP to create a conduit for signaling data between two nodes in the network for use by applications that operate on the ISUP.

Consider, for example, the case where it is necessary to send signaling data between two public telephone exchanges (PBXs) that are outside the SS7 network (and for which the originating user 3 and the originating user 4 are respectively connected), this situation it is illustrated in Figure 2 where the PBXs are indicated by the reference numbers 1, 2 and are connected to respective exchanges 5, 6 of the SS7 network. The requirement of the signaling data of the PBXs is similar to exceed that which can be provided by lAM and SGM (ie any space in the lAM and SGM that remains idle after the indicators and parameters of the necessary ISDN call establishment have been included) which are generated by the ISUP 9,10. The solution provided by APM is to create a conduit through which the interface applications 7, 8, existing in two exchanges of the SS7 network 5, 6 to which the PBXs respectively connect, can communicate. When a call connection is required by the originating user 3 through the associated PBX 1, the signaling data is passed by the application 7 in the SS7 5 exchange for the ISUP 9. A lAM is then generated by the ISUP for transmission to the remote SS7 exchange 6. However, the lAM includes an additional indicator indicating that the additional APM messages are to be followed. This indicator, called the "APM segmentation indicator" is contained in the Application Transport Parameter (APP) that has the following multi-octet structure (1 to 4n): The APP also contains an Application Context Identifier (ACI) that identifies the application for which the APP is intended. Therefore, in the present example, the ACI identifies the APP as it is intended for the application of Interface PBX 8. The signaling data received from application 7 is then segmented into a series of APPs containing APMs, each with the appropriate segmentation and the established context indicators. Based on these indicators, the ISUP 10 in the receiving station SS7 6 is able to reassemble the signaling information and pass it, otherwise unaltered, to the associated PBX interface application 8. It is noted that the lAM and the subsequent APMs are delivered to the receiving SS7 exchange 6 based on the corresponding SS7 Point Code which is included in each of the messages. It is also observed that in this process of end-to-end transmission (or direct connection) the lAMb and the AOMs are not "open" at any intermediate nodes present between the two exchanges. It is proposed here to make use of the APMs to transmit the additional user's address information that can not be included in a transmitted LAM during a call setup phase. This extends the use of the APM beyond providing only one conduit through the network (and ISUP) for "external" applications. Assume that it is desired to transport a relatively large amount of source user address information from the originating SS7 exchange 5 to the exchange SS7 exchange 6 during a call set-up phase., so that all this information can not be included in the associated individual LAM (or more specifically, the LAM APP). Any overload address information may be sent in subsequent APP containing APMs. However, this requires the definition of a new identifier referred to here as "UNÍ" which identifies the APP, for a receiver node as it transports (conventional) the direct connection data transfer (identifier = 0) or the transfer of monodirectional data (identifier = 1). this identifier can be assigned to an appropriate reservation identifier of the APP, for example bit 7 of octet 2 as shown in the previous table. The UNI identifier allows the intermediate nodes (for example the hubs) to jump to the segment reassembly process, saving time and processing in this way in the call establishment phase. More particularly, the intermediate nodes will only reassemble those segments belonging to the APPs for which the identifier UNIX a is set, ie in relation to the direct connection data transfers. When the UNI identifier is set to 1, the APP is passed unaltered to the next node. At the destination exchange, the basic call set-up procedure first extracts the APP from within IAM or APM. Check later to see if the UNI identifier is set to 3. If so, then the procedure knows that the message is one of a sequence of messages that require recombination in the exchange. The APP contains a specific Application Context Identifier (octet 1) that identifies the application for which the information transported was intended. In the present example, this request will be an application that makes use of the address information of the originating party. This process is generally illustrated in Figure 3a. Figure 3B illustrates in more detail the "Re-assemble segment" operation of Figure 3A. Note that only those APPs that have the same Local Segment Reference (SLR) are combined. It will be appreciated that further modifications may be made to the above-described embodiment without departing from the scope of the present invention. For example, while the previous example has been related to the transmission of the address information of the originating user, the present invention can be applied to transmit other types of information. In certain circumstances, the transmitted information (in this case, the user identity information) may be required for a service application that resides in an intermediate node between the exchanges 5, 6. This application may be, for example, an application of billing in a charge node ,. This requires the help of the ISUP to collect the information present in the lAM. The collection is executed when the service application sends an explicit request to the ISUP for APP activation pertaining to the transfer of user identity information. Upon receipt of two APP information elements within a lAM, the ISUP in the intermediate node is not able to distinguish the APP that transfers the user identity information from the other APP (transporting specific direct connection application data). To overcome this problem, the UNI indicator is used by the ISUP to indicate whether the APP refers to a direct connection association context or if it is part of the basic call context (and does not belong to the predefined application).

Claims (11)

1. CLAIMS 1. A method to transmit originating user address information in a telecommunications network using Signaling System No. 7, the method comprising conducting a call set-up phase between two nodes of the telecommunications network to reserve a channel for user data, the establishment phase comprising: transmitting an Initial Address Message from the first node to the subsequent node, the Initial Address Message containing an indicator of the Application Transfer Mechanism to notify the subsequent node that the information address will be transmitted in one or more subsequent Application Transfer Mechanism Messages; and transmit one or more Application Transfer Mechanism Messages from the first node to the subsequent node.
2. 2. A method according to claim 1, characterized in that the Initial Address Message and the Application Transfer Mechanism Message (s) each contain an Application Transport Parameter (APP) that translates the address information.
3. 3. A method according to claim 2, characterized in that each APP contains a Unidirectional Indicator to indicate to a receiving node whether the APP is part of a direct connection transmission or whether the APP refers to a basic call setup context.
4. 4. A method according to any of the preceding claims, characterized in that the Initial Address Message contains a limited amount of address information of the originating user.
5. 5. A method according to any of the preceding claims, characterized in that the address information of the originating user transmitted in one or more Messages of the Application Transfer Mechanism includes at least one of: the geographic location of the originating user; the user ID of the logical source; the logical subscriber ID; the user ID of physical origin; and the name of the originating user.
6. 6. A method according to any of the preceding claims, characterized in that the Initial Address Message and the Mechanism Message (s) Application transfers are transmitted over the telecommunications network in respective individual data packets.
7. 7. A method according to claim 6, characterized in that the last message of the transmitted Application Transfer Mechanism contains an indicator set to indicate to the receiving node that the message is the last message of the Application Transfer Mechanism.
8. 8. Apparatus for transmitting originating user address information in a telecommunications network using Signaling System No. 7, characterized in that a call set-up phase is conducted between the two nodes of the telecommunication network to reserve a channel for data of user, the apparatus comprising: first processing means provided in the first node and placed to generate an Initial Address Message and to transmit this message from the first node to the subsequent node, the Initial Address Message containing an indicator of the Application Transfer to notify the second node that the address information will be transmitted in one or more Application Transfer Mechanism Messages; and second processing means placed to generate one or more Application Transfer Mechanism Messages and to transmit the message (s) from the first node to the subsequent node.
9. 9. Apparatus according to claim 8, characterized in that the first and second processing means are provided by a suitably programmed computer system.
10. 10. A method of transmitting information in a telecommunications network, which uses Signaling System No. 7, during a call establishment phase between two nodes of the network, the information that is transmitted in a monodirectional form from a first of the nodes to the subsequent node and that is intended to be for an application present in the subsequent node, the method comprising: transmitting an Initial Address Message from the first node to the node Subsequently, the Initial Address Message containing an Application Transfer Mechanism indicator to notify the subsequent node that the information will be transmitted in one or more Messages of the Application Transfer Mechanism; and transmitting said one or more Application Transfer Mechanism Messages from the first node to the subsequent node, the method further comprising including in the or each message of the Application Transfer Mechanism a signal to indicate to a receiving node whether the message is or not a monodirectional message.
11. 11. A method according to claim 10, characterized in that the subsequent node is an intermediate node in the transmission path of said information, the method comprising entrusting the Application Transfer Mechanism Messages received to a subsequent node in an unaltered state when the messages contain a monodirectional indicator which is not established.