WO2021003737A1

WO2021003737A1 - Terminating a service to a client

Info

Publication number: WO2021003737A1
Application number: PCT/CN2019/095600
Authority: WO
Inventors: Erqun SUN; Debashish PATTNAIK
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2019-07-11
Filing date: 2019-07-11
Publication date: 2021-01-14

Abstract

There is provided a method performed by a proxy-call session control function (P-CSCF) node of a network for terminating a service to a client of the network. The method comprises receiving (102), from a push notification service (PNS) node of the network, location information indicative of a location of the client in the network. The method also comprises, in response to receiving, from an internet protocol multimedia subsystem (IMS) network to which the client is registered, a request to terminate the service to the client, forwarding (104) the received request to the client using the received location information.

Description

TERMINATING A SERVICE TO A CLIENT

Technical Field

The disclosure relates to methods for terminating a service to a client of a network and nodes configured to operate in accordance with the methods.

Background

A push notification (also known as a server push notification) is the delivery of information to a computing device from an application server where the request for a transaction is initiated by the server rather than by an explicit request from the client. In order to save resources (e.g. battery life) , some devices and operating systems suspend applications when the applications are not used. Generally, internal timers are used to wake the applications. However, in some cases, it is not possible to use internal timers to wake applications, nor will incoming network traffic wake applications. An alternative is to use a push notification service (PNS) to wake applications. Typically, each operating system uses a dedicated PNS.

Figure 1 illustrates a third generation partnership project (3GPP) network that uses a push service in the delivery of internet protocol (IP) multimedia services.

The network illustrated in Figure 1 comprises an application (App) running on a device, a proxy-call session control function (P-CSCF) node, an IP multimedia subsystem (IMS) core network, an access gateway (AGW) , and a push service application server (AS) . The App is an IMS application. The device can, for example, be a user equipment (UE) , such as a smart phone. The App and the P-CSCF node communicate using an interface (namely, a Gm’ interface) over a wireless local area network (WLAN) , the P-CSCF node and the IMS core network communicate using an interface (namely, a Gm’ interface) , the IMS core network and the AGW communicate using an interface (namely, an Mb interface) , and the AGW and the App communicate using an interface (namely, an Mb interface) .

The 3GPP has defined a push notification in the P-CSCF node, which supports sending push notifications to the push service. The push notification is used to wake up a client in an operating system of a device for terminating a service, such as a Wi-Fi calling service. In the network illustrated in Figure 1, the client is the App. The client may also be referred to as a user agent (UA) . The P-CSCF is responsible for sending a push request to the push service AS to wake up the App when there is a request to terminate a service targeted to that App, or when the P-CSCF wants to wake up the App for re-registration at the IMS core network.

Figure 2 is a signalling diagram illustrating an exchange of signals in this respect. As illustrated in Figure 2, the request to terminate a service (e.g. a session initiation protocol (SIP) session) is sent by the IMS core network to the P-CSCF. At the P-CSCF, a registration session and previously stored push notification (PN) parameters are identified. Also, at the P-CSCF, the request to terminate the service is buffered until the target push client wakes up.

When there is an incoming request to terminate a service (e.g. a call) targeted for the push client, the P-CSCF node constructs a push request (or push notification request) and sends the push request to a PNS. The PNS sends the push notification request to the push client to wake the push client. Once the push client wakes up, it re-establishes its connection with the P-CSCF. The push client initiates a transport layer security (TLS) connection with the P-CSCF and also initiates IMS re-registration with the P-CSCF. When re-registering at the IMS core network, the push client transmits push service information to the P-CSCF node. The information includes an address of the push service AS and additional information required by a device vendor to identify the push client. The P-CSCF initiates IMS registration with the IMS core network and the IMS core network notifies the P-CSCF that the IMS registration is successful. The P-CSCF notifies the push client that the IMS registration is successful and sends a request to the push client to terminate the service.

Thus, in this way, the push client is re-registered at the IMS core network and subsequently receives the incoming request to terminate the service targeted for the push client and handles that request to terminate a service accordingly. The establishment of the service is successful.

An IP multimedia subsystem (IMS) is one of the most complex network functions virtualization (NFV) instances and requires extremely Iow end-to-end latency (e.g. up to 40 msec) in order to be considered acceptable for subscribers. However, the existing push notification mechanism described earlier requires the client to re-register at the IMS core network after it is awakened by a PNS and re-establish the transport connection before an incoming request to terminate a service (namely, a terminating INVITE) can be forwarded by P-CSCF to the device, which inherently delays the service setup procedures and establishment. As such, the existing push notification mechanism adds latency to the end-to-end service setup.

There is thus a need for an improved technique, which is aimed at addressing at least some of the problems associated with existing algorithms.

Summary

It is an object to obviate or eliminate at least some of the above-described disadvantages associated with existing techniques and provide an improved technique for terminating a service to a client of a network.

Therefore, according to an aspect, there is provided a method performed by a proxy-call session control function (P-CSCF) node of a network for terminating a service to a client of the network. The method comprises receiving, from a push notification service (PNS) node of the network, location information indicative of a location of the client in the network. The method also comprises, in response to receiving, from an internet protocol multimedia subsystem (IMS) network to which the client is registered, a request to terminate the service to the client, forwarding the received request to the client using the received location information.

There is thus provided an improved method for terminating a service to a client of a network. In particular, the method increases the speed of terminating a session at a client, reduces the end-to-end latency for terminating a session at a client, and reduces network signals. In this way, the efficiency of the network resources is increased, the session is established faster, and network maintenance becomes faster, easier and less costly. This provides a more user friendly experience. This is possible since the P-CSCF node (e.g. proactively) receives the location information of the client from the PNS node and forwards the request to terminate the service directly to the client. This ensures that the client is no longer required to explicitly (re) register itself to the IMS network through the P-CSCF node and re-establish the transport connection every time the client transitions to awake mode (from sleep mode) . The delays in the service setup procedures and establishment are reduced in this way.

In some embodiments, the method may comprise subscribing the P-CSCF node to the PNS node for the P-CSCF node to receive the location information. In some embodiments, the method may comprise receiving the location information in response to the client changing location in the network and/or at predefined time intervals. In this way, the P-CSCF node is aware of the latest (or most recent, e.g. current) location information of the client. Thus, the P-CSCF node is no longer required to buffer the request to terminate the service, which saves on computing resources. Moreover, it possible for the P-CSCF node to directly forward the request to terminate the service to the client based on the latest (or most recent, e.g. current) location information of the client, which optimises signalling.

In some embodiments, the method may comprise, in response to receiving the request to terminate the service to the client, transmitting a request to the PNS node for the location information and receiving the location information in response to the transmitted request. In this way, traffic in the network can be reduced and signalling is optimised, since the P-CSCF requests the location information of the client when it is required and any other unnecessary signalling can be avoided. Moreover, the location information is likely to be the latest (or most recent, e.g. current) location information of the client, since it is requested at the time it is required.

According to another aspect, there is provided a proxy-call session control function (P-CSCF) node configured to operate in accordance with the method described earlier in respect of the P-CSCF node. In some embodiments, the P-CSCF node may comprise processing circuitry and at least one memory for storing instructions which, when executed by the processing circuitry, cause the P-CSCF node to operate in accordance with the method described earlier in respect of the P-CSCF node. The P-CSCF node thus provides the advantages discussed earlier in respect of the method performed by the P-CSCF node.

According to another aspect, there is provided a method performed by a PNS node of a network for terminating a service to a client of the network. The method comprises acquiring, from the client, location information indicative of a location of the client in the network and transmitting the acquired location information to a P-CSCF node of the network for use by the P-CSCF node in terminating the service to the client. The method performed by the PNS node thus provides the advantages discussed earlier in respect of the method performed by the P-CSCF node.

In some embodiments, the method may comprise subscribing the P-CSCF node to the PNS node for the P-CSCF node to receive the location information. In some embodiments, the method may comprise acquiring the location information in response to the client changing location in the network and/or at predefined time intervals. In this way, the PNS node acquires the latest (or most recent, e.g. current) location information of the client.

In some embodiments, the method may comprise acquiring the location information in response to receiving a request for the information from the P-CSCF node. In this way, traffic in the network can be reduced and signalling is optimised, since the location information of the client is acquired when it is required and any other unnecessary signalling can be avoided. Moreover, the location information is likely to be the latest (or most recent, e.g. current) location information of the client, since it is acquired at the time it is required.

According to another aspect, there is provided a PNS node configured to operate in accordance with the method described earlier in respect of the PNS node. In some embodiments, the PNS node may comprise processing circuitry and at least one memory for storing instructions which, when executed by the processing circuitry, cause the PNS node to operate in accordance with the method described earlier in respect of the PNS node. The PNS node thus provides the advantages discussed earlier in respect of the method performed by the PNS node.

According to another aspect, there is provided a method performed by a client of a network for terminating a service to the client. The method comprises transmitting, to a PNS node of the network, location information indicative of a location of the client in the network for use by a P-CSCF node of the network in terminating the service to the client. The method performed by the client thus provides the advantages discussed earlier in respect of the method performed by the P-CSCF node.

In some embodiments, the method may comprise transmitting the location information to the PNS node in response to the client changing location in the network and/or at predefined time intervals. In this way, the PNS node is provided with the latest (or most recent, e.g. current) location information of the client.

In some embodiments, the method may comprise transmitting the location information to the PNS node in response to the PNS node receiving a request for the information from the P-CSCF node. In this way, traffic in the network can be reduced and signalling is optimised, since the location information of the client is transmitted when it is required and any other unnecessary signalling can be avoided. Moreover, the location information is likely to be the latest (or most recent, e.g. current) location information of the client, since it is transmitted at the time it is required.

According to another aspect, there is provided a client configured to operate in accordance with the method described earlier in respect of the client. In some embodiments, the client may comprise processing circuitry and at least one memory for storing instructions which, when executed by the processing circuitry, cause the client to operate in accordance with the method described earlier in respect of the client. The client thus provides the advantages discussed earlier in respect of the method performed by the client.

According to another aspect, there is provided a system. The system may comprise any one or more of a P-CSCF node as described earlier, a PNS node as described earlier and a client as described earlier. The system thus provides the advantages discussed earlier in respect of the method performed by the P-CSCF node, the PNS node and the client.

According to another aspect, there is provided a computer program comprising instructions which, when executed by processing circuitry, cause the processing circuitry to perform the method described earlier. The computer program thus provides the advantages discussed earlier in respect of the method performed by the P-CSCF node, the PNS node and the client.

According to another aspect, there is provided a computer program product, embodied on a non-transitory machine-readable medium, comprising instructions which are executable by processing circuitry to cause the processing circuitry to perform the method described earlier. The computer program product thus provides the advantages discussed earlier in respect of the method performed by the P-CSCF node, the PNS node and the client.

Therefore, an improved technique for terminating a service to a client is provided.

Brief Description of The Drawings

For a better understanding of the idea, and to show how it may be put into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

Figure 1 is a block diagram illustrating an existing network;

Figure 2 is a signalling diagram illustrating an exchange of signals for terminating a service to a client according to existing techniques;

Figure 3 is a block diagram illustrating a P-CSCF node according to an embodiment;

Figure 4 is a block diagram illustrating a method performed by a P-CSCF node according to an embodiment;

Figure 5 is a block diagram illustrating a PNS node according to an embodiment;

Figure 6 is a block diagram illustrating a method performed by a PNS node according to an embodiment;

Figure 7 is a block diagram illustrating a client according to an embodiment;

Figure 8 is a block diagram illustrating a method performed by a client according to an embodiment;

Figure 9 is a block diagram illustrating a system according to an embodiment;

Figure 10 is a block diagram illustrating a system according to an embodiment;

Figure 11 is a signalling diagram illustrating an exchange of signals for registering a client according to an embodiment;

Figure 12 is a signalling diagram illustrating an exchange of signals for terminating a service to a client according to an embodiment;

Figure 13 is a signalling diagram illustrating an exchange of signals for terminating a service to a client according to an embodiment;

Figure 14 is a block diagram illustrating a P-CSCF node according to an embodiment;

Figure 15 is a block diagram illustrating a PNS node according to an embodiment; and

Figure 16 is a block diagram illustrating a client according to an embodiment.

Detailed Description

As mentioned earlier, an improved technique for terminating a service to a client of a network is provided. Herein, a service can be any service that terminates at a client. Examples of a service include, but are not limited to, an application, a session, a call service (e.g. a Wi-Fi calling service) , a multimedia telephony service, a voice over long term evolution (VoLTE) service, an enriched communication service, or any other service that terminates at a client. The service may be any IP multimedia subsystem (IMS) based service. The act of terminating a service to a client is the delivery of the service to the client.

Figure 3 illustrates a proxy-call session control function (P-CSCF) node 10 in accordance with an embodiment. The P-CSCF node 10 is for terminating a service to a client of the network. The P-CSCF node 10 is a node of the network.

As illustrated in Figure 3, the P-CSCF node 10 comprises processing circuitry (or logic) 12. The processing circuitry 12 controls the operation of the P-CSCF node 10 and can implement the method described herein in respect to the P-CSCF node 10. The processing circuitry 12 of the P-CSCF node 10 can comprise one or more processors, processing units, multi-core processors or modules that are configured or programmed to control the P-CSCF node 10 in the manner described herein. In particular implementations, the processing circuitry 12 of the P-CSCF node 10 can comprise a plurality of software and/or hardware modules that are each configured to perform, or are for performing, individual or multiple steps of the method described herein.

Briefly, the processing circuitry 12 of the P-CSCF node 10 is configured to receive, from a push notification service (PNS) node of the network, location information indicative of a location of the client in the network. The processing circuitry 12 of the P-CSCF node 10 is also configured to, in response to receiving, from an internet protocol multimedia subsystem (IMS) network to which the client is registered, a request to terminate the service to the client, forward the received request to the client using the received location information.

As illustrated in Figure 3, the P-CSCF node 10 may optionally comprise memory 14. The memory 14 of the P-CSCF node 10 can comprise a volatile memory or a non-volatile memory. In some embodiments, the memory 14 of the P-CSCF node 10 may comprise a non-transitory media. Examples of the memory 14 of the P-CSCF node 10 include, but are not limited to, a random access memory (RAM) , a read only memory (ROM) , a mass storage media such as a hard disk, a removable storage media such as a compact disk (CD) or a digital video disk (DVD) , and/or any other memory.

The processing circuitry 12 of the P-CSCF node 10 can be connected to the memory 14 of the P-CSCF node 10. In some embodiments, the memory 14 of the P-CSCF node 10 may be for storing program code or instructions which, when executed by the processing circuitry 12 of the P-CSCF node 10, cause the P-CSCF node 10 to operate in the manner described herein in respect of the P-CSCF node 10. For example, in some embodiments, the memory 14 of the P-CSCF node 10 may be configured to store program code or instructions that can be executed by the processing circuitry 12 of the P-CSCF node 10 to cause the P-CSCF node 10 to operate in accordance with the method described herein in respect of the P-CSCF node 10. Alternatively or in addition, the memory 14 of the P-CSCF node 10 can be configured to store any parameters, requests, responses, indications, information, data, notifications, signals, or similar, that are described herein. The processing circuitry 12 of the P-CSCF node 10 may be configured to control the memory 14 of the P-CSCF node 10 to store any parameters, requests, responses, indications, information, data, notifications, signals, or similar, that are described herein.

In some embodiments, as illustrated in Figure 3, the P-CSCF node 10 may optionally comprise a communications interface 16. The communications interface 16 of the P-CSCF node 10 can be connected to the processing circuitry 12 of the P-CSCF node 10 and/or the memory 14 of P-CSCF node 10. The communications interface 16 of the P-CSCF node 10 may be operable to allow the processing circuitry 12 of the P-CSCF node 10 to communicate with the memory 14 of the P-CSCF node 10 and/or vice versa. The communications interface 16 of the P-CSCF node 10 can be configured to transmit and/or receive any parameters, requests, responses, indications, information, data, notifications, signals, or similar, that are described herein. In some embodiments, the processing circuitry 12 of the P-CSCF node 10 may be configured to control the communications interface 16 of the P-CSCF node 10 to transmit and/or receive any parameters, requests, responses, indications, information, data, notifications, signals, or similar, that are described herein.

Although the P-CSCF node 10 is illustrated in Figure 3 as comprising a single memory 14, it will be appreciated that the P-CSCF node 10 may comprise at least one memory (i.e. a single memory or a plurality of memories) 14 that operate in the manner described herein. Similarly, although the P-CSCF node 10 is illustrated in Figure 3 as comprising a single communications interface 16, it will be appreciated that the P-CSCF node 10 may comprise at least one communications interface (i.e. a single communications interface or a plurality of communications interface) 16 that operate in the manner described herein.

It will also be appreciated that Figure 3 only shows the components required to illustrate an embodiment of the P-CSCF node 10 and, in practical implementations, the P-CSCF node 10 may comprise additional or alternative components to those shown.

Figure 4 is a flowchart illustrating a method performed by a P-CSCF node 10 of a network in accordance with an embodiment. The method is for terminating a service to a client of the network. The P-CSCF node 10 described earlier with reference to Figure 3 is configured to operate in accordance with the method of Figure 4. The method can be performed by or under the control of the processing circuitry 12 of the P-CSCF node 10.

With reference to Figure 4, at block 102, location information indicative of a location of the client in the network is received from a PNS node of the network. More specifically, the processing circuitry 12 of the P-CSCF node 10 receives the location information (e.g. via the communications interface 16 of the P-CSCF node 10) . The location information referred to herein can be any information that indicates a location of the client in the network, e.g. the location at which the client can be contacted in the network. In some embodiments, the location information may be referred to as contact information or contact location information ( “<contact>” ) . Examples of the location information include, but are not limited to, an IP address of the client in the network, a fully qualified domain name (FQDN) of the client in the network, a port of the client in the network, and/or any other information indicative of the location of the client in the network.

In some embodiments, the P-CSCF node 10 may subscribe to the PNS node for the P-CSCF node 10 to receive the location information. More specifically, the processing circuitry 12 of the P-CSCF node 10 may subscribe the P-CSCF node 10 to the PNS node for the P-CSCF node 10 to receive the location information.

In some embodiments, the location information may be received in response to the client changing location in the network and/or at predefined time intervals. In embodiments that are responsive to the client changing location in the network, the location information may be received as and when the client changes its location. Alternatively or in addition, in some embodiments, in response to receiving the request to terminate the service to the client, a request may be transmitted to the PNS node for the location information. More specifically, the processing circuitry 12 of the P-CSCF node 10 may transmit a request to the PNS node for the location information (e.g. via the communications interface 16 of the P-CSCF node 10) . In these embodiments, the location information may be received in response to the transmitted request for the location information.

Returning back to Figure 4, at block 104, in response to receiving, from an IMS network (e.g. an IMS core network) to which the client is registered, a request to terminate the service to the client, the received request is forwarded to the client using the received location information. More specifically, the processing circuitry 12 of the P-CSCF node 10 forwards the received request to the client (e.g. via the communications interface 16 of the P-CSCF node 10) .

Although not illustrated in Figure 4, in some embodiments, the received location information may be stored in at least one memory, such as at least one memory 14 (e.g. at least one local repository) of the P-CSCF node 10. Thus, in some embodiments, at least one memory can be configured to store the received location information. In some embodiments, the processing circuitry 12 of the P-CSCF node 10 can be configured to control the at least one memory to store the received location information.

Figure 5 illustrates a push notification service (PNS) node 20 in accordance with an embodiment. The PNS node 20 is for terminating a service to a client of the network. The PNS node 20 is a node of the network.

As illustrated in Figure 5, the PNS node 20 comprises processing circuitry (or logic) 22. The processing circuitry 22 controls the operation of the PNS node 20 and can implement the method described herein in respect to the PNS node 20. The processing circuitry 22 of the PNS node 20 can comprise one or more processors, processing units, multi-core processors or modules that are configured or programmed to control the PNS node 20 in the manner described herein. In particular implementations, the processing circuitry 22 of the PNS node 20 can comprise a plurality of software and/or hardware modules that are each configured to perform, or are for performing, individual or multiple steps of the method described herein.

Briefly, the processing circuitry 22 of the PNS node 20 is configured to acquire, from the client, location information indicative of a location of the client in the network and transmit the acquired location information to a P-CSCF node of the network for use by the P-CSCF node in terminating the service to the client.

As illustrated in Figure 5, the PNS node 20 may optionally comprise memory 24. The memory 24 of the PNS node 20 can comprise a volatile memory or a non-volatile memory. In some embodiments, the memory 24 of the PNS node 20 may comprise a non-transitory media. Examples of the memory 24 of the P-CSCF node 10 include, but are not limited to, a random access memory (RAM) , a read only memory (ROM) , a mass storage media such as a hard disk, a removable storage media such as a compact disk (CD) or a digital video disk (DVD) , and/or any other memory.

The processing circuitry 22 of the PNS node 20 can be connected to the memory 24 of the PNS node 20. In some embodiments, the memory 24 of the PNS node 20 may be for storing program code or instructions which, when executed by the processing circuitry 22 of the PNS node 20, cause the PNS node 20 to operate in the manner described herein in respect of the PNS node 20. For example, in some embodiments, the memory 24 of the PNS node 20 may be configured to store program code or instructions that can be executed by the processing circuitry 22 of the PNS node 20 to cause the PNS node 20 to operate in accordance with the method described herein in respect of the PNS node 20. Alternatively or in addition, the memory 24 of the PNS node 20 can be configured to store any parameters, requests, responses, indications, information, data, notifications, signals, or similar, that are described herein. The processing circuitry 22 of the PNS node 20 may be configured to control the memory 24 of the PNS node 20 to store any parameters, requests, responses, indications, information, data, notifications, signals, or similar, that are described herein.

In some embodiments, as illustrated in Figure 5, the PNS node 20 may optionally comprise a communications interface 26. The communications interface 26 of the PNS node 20 can be connected to the processing circuitry 22 of the PNS node 20 and/or the memory 24 of PNS node 20. The communications interface 26 of the PNS node 20 may be operable to allow the processing circuitry 22 of the PNS node 20 to communicate with the memory 24 of the PNS node 20 and/or vice versa. The communications interface 26 of the PNS node 20 can be configured to transmit and/or receive any parameters, requests, responses, indications, information, data, notifications, signals, or similar, that are described herein. In some embodiments, the processing circuitry 22 of the PNS node 20 may be configured to control the communications interface 26 of the PNS node 20 to transmit and/or receive any parameters, requests, responses, indications, information, data, notifications, signals, or similar, that are described herein.

Although the PNS node 20 is illustrated in Figure 5 as comprising a single memory 24, it will be appreciated that the PNS node 20 may comprise at least one memory (i.e. a single memory or a plurality of memories) 24 that operate in the manner described herein. Similarly, although the PNS node 20 is illustrated in Figure 5 as comprising a single communications interface 26, it will be appreciated that the PNS node 20 may comprise at least one communications interface (i.e. a single communications interface or a plurality of communications interface) 26 that operate in the manner described herein.

It will also be appreciated that Figure 5 only shows the components required to illustrate an embodiment of the PNS node 20 and, in practical implementations, the PNS node 20 may comprise additional or alternative components to those shown.

Figure 6 is a flowchart illustrating a method performed by a PNS node 20 of a network in accordance with an embodiment. The method is for terminating a service to a client of the network. The PNS node 20 described earlier with reference to Figure 5 is configured to operate in accordance with the method of Figure 6. The method can be performed by or under the control of the processing circuitry 22 of the PNS node 20.

With reference to Figure 6, at block 202, location information indicative of a location of the client in the network is acquired from the client. More specifically, the processing circuitry 22 of the PNS node 20 acquires the location information from the client (e.g. via the communications interface 26 of the PNS node 20) .

At block 204 of Figure 6, the acquired location information is transmitted to a P-CSCF node 10 of the network for use by the P-CSCF node 10 in terminating the service to the client. More specifically, the processing circuitry 22 of the PNS node 20 transmits the location information to the P-CSCF node 10 (e.g. via the communications interface 26 of the PNS node 20) .

In some embodiments, the PNS node 20 may subscribe the P-CSCF node 10 to the PNS node 20 for the P-CSCF node 10 to receive the location information. More specifically, the processing circuitry 22 of the PNS node 20 may subscribe the P-CSCF node 10 to the PNS node 20 for the P-CSCF node 10 to receive the location information.

In some embodiments, the location information may be acquired in response to the client changing location in the network and/or at predefined time intervals. Similarly, in some of these embodiments, the acquired location information may be transmitted to the P-CSCF node 10 of the network in response to the client changing location in the network and/or at predefined time intervals. In embodiments that are responsive to the client changing location in the network, the location information may be acquired and transmitted as and when the client changes its location.

Alternatively or in addition, in some embodiments, the location information may be acquired in response to the PNS node 20 receiving a request (e.g. a push notification request) for the location information from the P-CSCF node. More specifically, the location information may be acquired in response to the processing circuitry 22 of the PNS node 20 receiving the request for the location information from the P-CSCF node (e.g. via the communications interface 26 of the PNS node 20) . For example, the processing circuitry 22 of the PNS node 20 may be configured to transmit a request (e.g. via the communications interface 26 of the PNS node 20) to the client 30 for the location information in response to receiving the request for the location information from the P-CSCF node. Thus, the processing circuitry 22 of the PNS node 20 may be configured to receive the location information from the client 30 in in this way.

Figure 7 illustrates a client 30 of a network in accordance with an embodiment. The client 30 is for terminating a service to the client 30. The client 30 described herein can, for example, be a user equipment (UE) such as a device or mobile device (e.g. a smart phone, a tablet, or any other device) . The client 30 described herein can be any client that supports push notifications and thus may also be referred to as a push client.

As illustrated in Figure 7, the client 30 comprises processing circuitry (or logic) 32. The processing circuitry 32 controls the operation of the client 30 and can implement the method described herein in respect to the client 30. The processing circuitry 32 of the client 30 can comprise one or more processors, processing units, multi-core processors or modules that are configured or programmed to control the client 30 in the manner described herein. In particular implementations, the processing circuitry 32 of the client 30 can comprise a plurality of software and/or hardware modules that are each configured to perform, or are for performing, individual or multiple steps of the method described herein.

Briefly, the processing circuitry 32 of the client 30 is configured to transmit, to a PNS node 20 of the network, location information indicative of a location of the client 30 in the network for use by a P-CSCF node 10 of the network in terminating the service to the client 30.

As illustrated in Figure 7, the client 30 may optionally comprise memory 34. The memory 34 of the client 30 can comprise a volatile memory or a non-volatile memory. In some embodiments, the memory 34 of the client 30 may comprise a non-transitory media. Examples of the memory 34 of the client 30 include, but are not limited to, a random access memory (RAM) , a read only memory (ROM) , a mass storage media such as a hard disk, a removable storage media such as a compact disk (CD) or a digital video disk (DVD) , and/or any other memory.

The processing circuitry 32 of the client 30 can be connected to the memory 34 of the client 30. In some embodiments, the memory 34 of the client 30 may be for storing program code or instructions which, when executed by the processing circuitry 32 of the client 30, cause the client 30 to operate in the manner described herein in respect of the client 30. For example, in some embodiments, the memory 34 of the client 30 may be configured to store program code or instructions that can be executed by the processing circuitry 32 of the client 30 to cause the client 30 to operate in accordance with the method described herein in respect of the client 30. Alternatively or in addition, the memory 34 of the client 30 can be configured to store any parameters, requests, responses, indications, information, data, notifications, signals, or similar, that are described herein. The processing circuitry 32 of the client 30 may be configured to control the memory 34 of the client 30 to store any parameters, requests, responses, indications, information, data, notifications, signals, or similar, that are described herein. In some embodiments, as illustrated in Figure 7, the client 30 may optionally comprise a communications interface 36. The communications interface 36 of the client 30 can be connected to the processing circuitry 32 of the client 30 and/or the memory 34 of client 30. The communications interface 36 of the client 30 may be operable to allow the processing circuitry 32 of the client 30 to communicate with the memory 34 of the client 30 and/or vice versa. The communications interface 36 of the client 30 can be configured to transmit and/or receive any parameters, requests, responses, indications, information, data, notifications, signals, or similar, that are described herein. In some embodiments, the processing circuitry 32 of the client 30 may be configured to control the communications interface 36 of the client 30 to transmit and/or receive any parameters, requests, responses, indications, information, data, notifications, signals, or similar, that are described herein.

Although the client 30 is illustrated in Figure 7 as comprising a single memory 34, it will be appreciated that the client 30 may comprise at least one memory (i.e. a single memory or a plurality of memories) 24 that operate in the manner described herein. Similarly, although the client 30 is illustrated in Figure 7 as comprising a single communications interface 36, it will be appreciated that the client 30 may comprise at least one communications interface (i.e. a single communications interface or a plurality of communications interface) 36 that operate in the manner described herein.

It will also be appreciated that Figure 7 only shows the components required to illustrate an embodiment of the client 30 and, in practical implementations, the client 30 may comprise additional or alternative components to those shown.

Figure 8 is a flowchart illustrating a method performed by a client 30 of a network in accordance with an embodiment. The method is for terminating a service to the client 30 of the network. The client 30 described earlier with reference to Figure 7 is configured to operate in accordance with the method of Figure 8. The method can be performed by or under the control of the processing circuitry 32 of the client 30.

With reference to Figure 8, at block 302, location information indicative of a location of the client 30 in the network is transmitted to a PNS node 20 of the network. More specifically, the processing circuitry 32 of the client 30 transmits the location information to the PNS node 20 (e.g. via the communications interface 36 of the client 30) . The location information is for use by a P-CSCF node 10 of the network in terminating the service to the client 30.

In some embodiments, the location information may be transmitted to the PNS node 20 in response to the client 30 changing location in the network and/or at predefined time intervals. In embodiments that are responsive to the client 30 changing location in the network, the location information may be transmitted to the PNS node 20 as and when the client 30 changes its location.

Alternatively or in addition, in some embodiments, the location information may be transmitted to the PNS node 20 in response to the PNS node 20 receiving a request for the information from the P-CSCF node 10. For example, the processing circuitry 32 of the client 30 may be configured to receive a request (e.g. via the communications interface 36 of the client 30) from the PNS node 20 for the location information in response to the PNS node 20 receiving the request for the location information from the P-CSCF node. Thus, the processing circuitry 32 of the client 30 may be configured to transmit the location information to the PNS node 20 (e.g. via the communications interface 36 of the client 30) in response to receiving the request for the information from the PNS node 20.

There is also provided a system. The system can comprise one or more P-CSCF nodes 10 as described herein, one or more PNS nodes 20 as described herein and/or one or more clients 30 as described herein.

Figure 9 is a block diagram illustrating a system according to an embodiment. In the illustrated embodiment of Figure 9, the system comprises a P-CSCF node 10, a PNS node 20, and a client 30. The P-CSCF node 10 is configured to operate in the manner described earlier with reference to Figures 3 and 4, the PNS node 20 is configured to operate in the manner described earlier with reference to Figures 5 and 6, and the client 30 is configured to operate in the manner described earlier with reference to Figures 7 and 8.

In more detail, in the illustrated embodiment of Figure 9, the P-CSCF node 10 subscribes to the PNS node 20 to receive location information indicative of a location of the client 30 in the network (as illustrated by arrow 402 in Figure 9) . For example, the P-CSCF node 10 may subscribe to the PNS node 20 for a locations service. The PNS node 20 transmits the location information to the P-CSCF node 10 and the P-CSCF node 10 receives the location information (as illustrated by arrow 404 in Figure 9) . The P-CSCF node 10 may store the received location information in at least one memory, such as at least one memory 14 (e.g. at least one local repository) of the P-CSCF node 10.

The PNS node 20 acquires the location information from the client 30 (as illustrated by arrow 406 in Figure 9) . The client 30 may keep updating the location information. In some embodiments, the P-CSCF node 10 may subscribe to the PNS node 20 to receive the location information in response to the client 30 changing location in the network and/or at predefined time intervals. Thus, in some embodiments, the PNS node 20 may acquire the location information from the client 30 in response to the client 30 changing location in the network and/or at predefined time intervals. In some embodiments, the acquisition of location information by the PNS node 20 may involve the client 30 transmitting the location information to the PNS node 20 and the PNS node 20 receiving the location information from the client 30. For example, in some embodiments, each time the client 30 changes location and/or at predefined time intervals, the PNS node 20 may send a notification to the P-CSCF node 10 to inform the P-CSCF node 10 of the latest (or most recent, e.g. current) location of the client 30.

The P-CSCF node 10 may receive, from an IMS network (e.g. an IMS core network) to which the client 30 is registered, a request to terminate a service to the client 30 (as illustrated by arrow 408 in Figure 9) . Prior to this, the client 30 may be idle. The P-CSCF node 10 forwards the received request to the client 30 (as illustrated by arrow 410 in Figure 9) using the received location information. In this way, the service to the client 30 can be terminated.

Figure 10 is a block diagram illustrating a system according to an embodiment. In the illustrated embodiment of Figure 10, the system comprises a P-CSCF node 10, a PNS node 20, and a client 30. The P-CSCF node 10 is configured to operate in the manner described earlier with reference to Figures 3 and 4, the PNS node 20 is configured to operate in the manner described earlier with reference to Figures 5 and 6, and the client 30 is configured to operate in the manner described earlier with reference to Figures 7 and 8.

In more detail, in the illustrated embodiment of Figure 10, the PNS node 20 acquires (e.g. fetches) location information from a client 30 (as illustrated by arrow 502 in Figure 10) . The location information is indicative of a location of the client 30 in the network. The PNS node 20 may connect to the client 30 via an interface.

The P-CSCF node 10 may receive, from an IMS network (e.g. an IMS core network) to which the client 30 is registered, a request to terminate a service to the client 30 (as illustrated by arrow 508 in Figure 10) . Prior to this, the client 30 may be idle. In response to receiving the request to terminate the service to client 30, the P-CSCF node 10 may transmit a request (e.g. a push notification request or GET request) to the PNS node 20 for the location information (as illustrated by arrow 506 in Figure 10) . For example, the P-CSCF node 10 may provide push notification (PN) parameters to the PNS node 20 to get the location information. Thus, the PNS node 20 may acquire the location information from the client 30 when invoked, e.g. in response to receiving the request for the location information. The PNS node 20 transmits the location information to the P-CSCF node 10 and the P-CSCF node 10 receives the location information (as illustrated by arrow 504 in Figure 10) . Thus, in effect, the PNS node 20 shares the location information of the client 30 with the P-CSCF node 10. The P-CSCF node 10 can now directly connect to the client 30.

Thus, the P-CSCF node 10 forwards the received request to terminate the service to the client 30 (as illustrated by arrow 510 in Figure 10) using the received location information. In this way, the service to the client 30 can be terminated. In some embodiments, the client 30 may send a notification (e.g. refresh-REGISTER) to the IMS network (not illustrated in Figure 10) to refresh its registration in order to prevent its registration from expiring and avail the services from IMS network. However, the client 30 is no longer required to re-register at the IMS network or initiate the setting up of a transport connection, such as a transport layer security (TLS) , towards the P-CSCF node 10.

Figure 11 is a signalling (or call flow) diagram illustrating an exchange of signals in an example embodiment. The exchange of signals is in a system. The system comprises a client (or push client) 30, a push service node 40, a P-CSCF node 10, an interrogating call session control function (I-CSCF) 50, a serving call session control function (S-CSCF) 60, a home subscriber server (HSS) 70, and an application server such as a telephony application server (TAS) 80. In more detail, Figure 11 depicts the client 30 registering at an IMS network (not illustrated) through a P-CSCF node 10.

As illustrated by arrow 602 of Figure 11, a request to register a service (e.g. an application) at the IMS network is sent by the client 30 to the push service node 40. In response to the request, as illustrated by arrow 604 of Figure 11, the push service node 40 sends a response indicating that the registration is successful. The response may comprise push service information. During registration, the push service node 40 may store the information used for push notification from the registration signalling. As illustrated by arrow 606 of Figure 11, the client 30 sends a request to the P-CSCF node 10 to register the client 30 at the IMS network. The request may comprise the push service information. At block 608 of Figure 11, no registration session is found by the P-CSCF node 10. Thus, as illustrated by arrow 610 of Figure 11, the P-CSCF node 10 sends a request to register the client 30 at the IMS network to the I-CSCF node 50 and, as illustrated by arrow 612 of Figure 11, the I-CSCF node 50 forwards the request to the S-CSCF node 60.

As illustrated by arrow 614 of Figure 11, the S-CSCF node 60 requests a profile for the client from the HSS 70 and, as illustrated by arrow 616 of Figure 11, the HSS 70 transmits the requested profile to the S-CSCF node 60. Although not illustrated, the S-CSCF node 60 may receive contact information of an application server (e.g. the TAS 80) from the HSS 70. At block 618 of Figure 11, the registration of the client 30 at the IMS network is treated by the S-CSCF node 60 as an initial registration at the IMS network. As illustrated by arrow 620 of Figure 11, the S-CSCF node 60 transmits a response, e.g. a 200OK (Registration) response, to the I-CSCF node 50 indicating that the registration is successful.

The S-CSCF node 60 maintains the contact information of the client 30. As illustrated by arrow 622 of Figure 11, the S-CSCF node 60 forwards a registration request to an application server (e.g. the TAS 80) requesting 3 ^rd party registration with the application server (e.g. the TAS 80) so that the client 30 can avail the (e.g. telephony) application services of the application server. As illustrated by arrow 624 of Figure 11, the application server (e.g. the TAS 80) contacts the HSS 70 to acquire identification information indicative of an identity of the client 30 in order to invoke services (telephony and/or supplementary services) from the application server (e.g. the TAS 80) . Although not illustrated, the application server (e.g. the TAS 80) may also acquire subscriber data for the client 30 from the HSS 70.

As illustrated by arrow 626 of Figure 11, the I-CSCF node 50 forwards the response received from the S-CSCF node 60, e.g. a 200OK (Registration) response, indicating that the registration is successful to the P-CSCF node 10. As illustrated by arrow 628 of Figure 11, the HSS 70 sends the acquired identification information and optionally also the subscriber data to application server (e.g. the TAS 80) , which may include information such as an IP multimedia public identity (IMPU) for the client 30, an IP multimedia private identity (IMPI) for the client 30 and/or a mobile station international subscriber directory number (MSISDN) for the client 30. The application server (e.g. the TAS 80) updates the contact information of the client 30 in its local database based on the information received from the HSS 70. As illustrated by arrow 630 of Figure 11, the application server (e.g. the TAS 80) sends a response, e.g. a 200OK (3PP Registration) response, to the S-CSCF node 60 indicating the successful 3 ^rd party registration of the client 30 in the application server (e.g. the TAS 80) . As illustrated by arrow 632 of Figure 11, the P-CSCF node 10 forwards the response received from the S-CSCF node 60, e.g. a 200OK (Registration) response, indicating that the registration is successful to the client 30.

Figure 12 is a signalling (or call flow) diagram illustrating an exchange of signals in an example embodiment. The exchange of signals is in a system. The system comprises an IMS network 90, a P-CSCF node 10, client (or push client) 30, and a PNS node 20. In more detail, Figure 12 depicts the P-CSCF node 10 terminating a service (e.g. a call) to the client 30. The establishment of terminating the service is accelerated by the P-CSCF node 10 handling register and invite sessions in parallel in both directions, i.e. in the core and the access network.

At block 702 of Figure 12, the client 30 is already registered with the IMS network 90. Although not illustrated in Figure 12, the client 30 may indicate its support for push notification by providing push notification (PN) parameters (e.g. pn-provider, pn-param, pn-prid) in the initial or previous requests to register with the IMS network, which are described earlier with reference to Figure 11.

Returning back to Figure 12, as illustrated by arrow 704 of Figure 12, the P-CSCF node 10 subscribes to the PNS node 20, e.g. over a push notification interface, to receive the location information. The P-CSCF node 10 subscribes to the PNS node 20 to avail the location service of getting notified of the location information of the client 30 from the PNS node 20, e.g. whenever the client 30 changes its contact location and/or at predefined time intervals. The client may at (e.g. regular) intervals update its location information, e.g. along with PN parameters, and notify the PNS node 20 accordingly. The PNS node 20 can also pull the location information of the client 30 either at (e.g. regular) intervals or on invocation.

As illustrated by arrow 706 of Figure 12, the PNS node 20 informs the P-CSCF node 10 that the subscription is successful. As illustrated by arrow 708 of Figure 12, the PNS node 20 transmits the acquired location information of the client 30 to the P-CSCF node 10. The P-CSCF node 10 subscription to the location service ensures that the P-CSCF node 10 always has the latest (or most recent, e.g. current) location information of the client 30. The P-CSCF node 10 may store the received location information of the client 30 in at least one memory (e.g. at least one local repository) of the P-CSCF node 10.

As illustrated by arrow 710 of Figure 12, a request to terminate a service (e.g. a session initiation protocol (SIP) session) is sent (or forwarded) is sent by the IMS network 90 to the P-CSCF node 10 and the request is received by the P-CSCF node 10. The request is intended for the client 30. At block 712 of Figure 12, a registration session and previously stored PN parameters (e.g. pn-provider, pn-param, pn-prid) are identified by the P-CSCF node 10. For example, the request received by the P-CSCF node 10 may comprise the PN parameters. The PN parameters indicate to the P-CSCF node 10 that the client supports push notifications.

At block 714 of Figure 12, the P-CSCF node 10 contains the location information. The P-CSCF node 10 subscription to the location service ensures it always has the latest (or most recent, e.g. current) location information of the client 30. The P-CSCF node 10 retrieves the contact information of the client 30 from the at least one memory (e.g. at least one local repository) of the P-CSCF node 10, e.g. based on the PN parameters. In this way, the PNS node 20 can directly respond to the P-CSCF node 10 with the location information of the client 30. The client 30 is no longer required to register at the P-CSCF node 10 and IMS network 90 each time the client 30 is in ‘wake up’ mode.

As illustrated by arrow 716 of Figure 12, the P-CSCF node 10 forwards the request to terminate the service to the client 30 at the location indicated by the (retrieved) location information. For example, the P-CSCF node 10 can trigger a new transport connection towards the (retrieved) location of the client 30 and can directly forward the (buffered) request to terminate the service to that location. As illustrated by arrow 718 of Figure 12, the client 30 responds to the request and the P-CSCF node 10 receives the response. For example, the P-CSCF node 10 may receive a 200OK response for the request. At block 720 of Figure 12, the service is successfully terminated at the client 30. The service may be established on a fast track.

Figure 13 is a signalling (or call flow) diagram illustrating an exchange of signals in an example embodiment. The exchange of signals is in a system. The system comprises an IMS network 90, a P-CSCF node 10, client (or push client) 30, and a PNS node 20. In more detail, Figure 13 depicts the P-CSCF node 10 terminating a service (e.g. a call or service) to the client 30. The establishment of terminating the service is accelerated by the P-CSCF node 10 handling register and invite sessions in parallel in both directions, i.e. in the core and the access network. In this illustrated example embodiment, the client (or push client) 30 is a user equipment (UE) but it will be understood that the client 30 may be any other client.

At block 802 of Figure 13, the client 30 is already registered with the IMS network 90. Although not illustrated in Figure 13, the client 30 may indicate its support for push notification by providing push notification (PN) parameters (e.g. pn-provider, pn-param, pn-prid) in the initial or previous requests to register with the IMS network, which are described earlier with reference to Figure 11.

Returning back to Figure 13, as illustrated by arrow 804, a request to terminate a service (e.g. a session initiation protocol (SIP) session) is sent (or forwarded) by the IMS network 90 to the P-CSCF node 10 and the request is received by the P-CSCF node 10. The request is intended for the client 30. At block 806 of Figure 13, a registration session and previously stored PN parameters (e.g. pn-provider, pn-param, pn-prid) are identified by the P-CSCF node 10. For example, the request received by the P-CSCF node 10 may comprise the PN parameters. The PN parameters indicate to the P-CSCF node 10 that the client supports push notifications. If the P-CSCF node 10 detects non-availability of a transport channel towards the client 30, the P-CSCF node 10 verifies that the client 30 supports push notifications by checking the buffered PN-parameters. The received request to terminate the service may be kept in at least one memory 14 (e.g. a local buffer of) the P-CSCF node 10 until a channel is open within a stipulated interval.

The P-CSCF node 10 constructs a request (e.g. a push notification request) for location information indicative of the location of the client 30 in the network and, as illustrated by arrow 808 of Figure 13, sends the request to the PNS node 20. For example, the P-CSCF node 10 may provide the PN parameters to the PNS node 20 to get the location information. At block 810 of Figure 13, the PNS node 20 acquires (e.g. by pulling or requesting) the location information from the client 30. Thus, the PNS node 20 can pull the location information of the client 30 by directly contacting the client, e.g. over a PN interface. As illustrated by arrow 812 of Figure 13, the PNS node 20 transmits the acquired location information to the P-CSCF node 10 and the P-CSCF node 10 receives the location information. In this way, the PNS node 20 can directly respond to the P-CSCF node 10 with the location information of the client 30. The client 30 is no longer required to register at the P-CSCF node 10 and IMS network 90 each time the client 30 is in ‘wake up’ mode.

As illustrated by arrow 814 of Figure 13, the P-CSCF node 10 forwards the request to terminate the service to the client 30. For example, the P-CSCF node 10 can trigger a new transport connection towards the location of the client 30 indicated by the received location information and can directly forward the (buffered) request to terminate the service to that location. As illustrated by arrow 816 of Figure 13, the client 30 responds to the request and the P-CSCF node 10 receives the response. For example, the P-CSCF node 10 may receive a 200OK response for the request. At block 818 of Figure 13, the service is successfully terminated at the client 30. The service may be established on a fast track.

Figure 14 is a block diagram illustrating a P-CSCF node 900 in accordance with an embodiment. The P-CSCF node 900 comprises a receiving module 902 configured to receive, from a PNS node of the network, location information indicative of a location of the client in the network. The P-CSCF node 900 comprises a forwarding module 904 configured to, in response to receiving) , from an IMS network to which the client is registered, a request to terminate the service to the client, forward the received request to the client using the received location information. The P-CSCF node 900 may operate in the manner described herein.

Figure 15 is a block diagram illustrating a PNS node 1000 in accordance with an embodiment. The PNS node 1000 comprises an acquiring module 1002 configured to acquire, from the client, location information indicative of a location of the client in the network. The PNS node 1000 comprises a transmitting module 1004 configured to transmit the acquired location information to a P-CSCF node 900 of the network for use by the P-CSCF node 900 in terminating the service to the client. The PNS node 1000 may operate in the manner described herein.

Figure 16 is a block diagram illustrating a client 1100 in accordance with an embodiment. The client 1100 comprises a transmitting module 1102 configured to transmit, to a PNS node 1000 of the network, location information indicative of a location of the client in the network for use by a P-CSCF node 900 of the network in terminating the service to the client. The client 1100 may operate in the manner described herein.

There is also a computer program comprising instructions which, when executed by processing circuitry (such as the processing circuitry 12 of the P-CSCF node 10, the processing circuitry 22 of the PNS node 20, and/or the processing circuitry 32 of the client 30 described earlier) , cause the processing circuitry to perform at least part of the method described herein. There is provided a computer program product, embodied on a non-transitory machine-readable medium, comprising instructions which are executable by processing circuitry (such as the processing circuitry 12 of the P-CSCF node 10, the processing circuitry 22 of the PNS node 20, and/or the processing circuitry 32 of the client 30 described earlier) to cause the processing circuitry to perform at least part of the method described herein. There is provided a computer program product comprising a carrier containing instructions for causing processing circuitry (such as the processing circuitry 12 of the P-CSCF node 10, the processing circuitry 22 of the PNS node 20, and/or the processing circuitry 32 of the client 30 described earlier) to perform at least part of the method described herein. In some embodiments, the carrier can be any one of an electronic signal, an optical signal, an electromagnetic signal, an electrical signal, a radio signal, a microwave signal, or a computer-readable storage medium.

The node and client functionality described herein can be performed by hardware. Thus, any one or more nodes described herein can be a hardware node and/or the client describe herein can be a hardware client. However, it will also be understood that at least part or all of the node and/or client functionality described herein can be virtualized. For example, the functions performed by any one or more nodes and/or the client can be implemented in software running on generic hardware that is configured to orchestrate the node and/or client functionality. Thus, in some embodiments, any one or more nodes described herein can be a virtual node and/or the client can be a virtual client. In some embodiments, at least part or all of the node and/or client functionality described herein may be performed in a network enabled cloud. The node and/or client functionality described herein may all be at the same location or at least some of the node functionality may be distributed.

It will be understood that at least some or all of the method steps described herein can be automated in some embodiments. That is, in some embodiments, at least some or all of the method steps described herein can be performed automatically.

Thus, in the manner described herein, there is advantageously provided an improved technique for terminating a service to a

client

30, 1100.

It should be noted that the above-mentioned embodiments illustrate rather than limit the idea, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. The word “comprising” does not exclude the presence of elements or steps other than those listed in a claim, “a” or “an” does not exclude a plurality, and a single processor or other unit may fulfil the functions of several units recited in the claims. Any reference signs in the claims shall not be construed so as to limit their scope.

Claims

A method performed by a proxy-call session control function, P-CSCF, node of a network for terminating a service to a client of the network, the method comprising:

receiving (102, 404, 504, 708, 812) , from a push notification service, PNS, node of the network, location information indicative of a location of the client in the network; and

in response to receiving, from an internet protocol multimedia subsystem, IMS, network to which the client is registered, a request to terminate the service to the client, forwarding (104, 410, 510, 716, 814) the received request to the client using the received location information.
A method as claimed in claim 1, the method comprising:

subscribing (402, 704) the P-CSCF node to the PNS node for the P-CSCF node to receive the location information.
A method as claimed in any of the preceding claims, the method comprising:

receiving (404, 708) the location information in response to the client changing location in the network and/or at predefined time intervals.
A method as claimed in any of the preceding claims, the method comprising:

in response to receiving (508, 804) the request to terminate the service to the client, transmitting (506, 808) a request to the PNS node for the location information; and

receiving (504, 812) the location information in response to the transmitted request.
A proxy-call session control function, P-CSCF, node (10) configured to operate in accordance with any of claims 1 to 4.
A P-CSCF node (10) according to claim 5, wherein the P-CSCF node (10) comprises:

processing circuitry (12) ; and

at least one memory (14) for storing instructions which, when executed by the processing circuitry (12) , cause the P-CSCF node (10) to operate in accordance with any of claims 1 to 4.
A method performed by a push notification service, PNS, node of a network for terminating a service to a client of the network, the method comprising:

acquiring (202, 406, 502, 810) , from the client, location information indicative of a location of the client in the network; and

transmitting (204, 404, 504, 708, 812) the acquired location information to a proxy-call session control function, P-CSCF, node of the network for use by the P-CSCF node in terminating the service to the client.
A method as claimed in claim 7, the method comprising:

subscribing (402, 704) the P-CSCF node to the PNS node for the P-CSCF node to receive the location information.
A method as claimed in any of claims 7 to 8, the method comprising:

acquiring (406) the location information in response to the client changing location in the network and/or at predefined time intervals.
A method as claimed in any of claims 7 to 9, the method comprising:

acquiring (502, 810) the location information in response to receiving (506, 808) a request for the location information from the P-CSCF node.
A push notification service, PNS, node (20) configured to operate in accordance with any of claims 7 to 10.
A PNS node (20) according to claim 11, wherein the PNS node (20) comprises:

processing circuitry (22) ; and

at least one memory (24) for storing instructions which, when executed by the processing circuitry (22) , cause the PNS node (20) to operate in accordance with any of claims 7 to 10.
A method performed by a client of a network for terminating a service to the client, the method comprising:

transmitting (302, 406, 502) , to a push notification service, PNS, node of the network, location information indicative of a location of the client in the network for use by a proxy-call session control function, P-CSCF, node of the network in terminating the service to the client.
A method as claimed in claim 13, the method comprising:

transmitting (406) the location information to the PNS node in response to the client changing location in the network and/or at predefined time intervals.
A method as claimed in any of claims 13 to 14, the method comprising:

transmitting (502) the location information to the PNS node in response to the PNS node receiving (506) a request for the information from the P-CSCF node.
A client (30) configured to operate in accordance with any of claims 13 to 15.
A client (30) according to claim 16, wherein the client (30) comprises:

processing circuitry (32) ; and

at least one memory (34) for storing instructions which, when executed by the processing circuitry (32) , cause the client (30) to operate in accordance with any of claims 13 to 15.
A system comprising any one or more of:

a P-CSCF node (10) as claimed in any of claims 5 to 6;

a PNS node (20) as claimed in any of claims 11 to 12; and

a client (30) as claimed in any of claims 16 to 17.
A computer program comprising instructions which, when executed by processing circuitry, cause the processing circuitry to perform the method according to any one or more of claims 1 to 4, 7 to 10 and 13 to 15.
A computer program product, embodied on a non-transitory machine-readable medium, comprising instructions which are executable by processing circuitry to cause the processing circuitry to perform the method according to any one or more of claims 1 to 4, 7 to 10 and 13 to 15.