Abstract: A method of maintaining SIP registration in a SIP network for a SIP User Agent resident on a client device, the SIP User Agent having registered with a Push Provider to receive Push Notifications via an Operating System of the client device. The method comprises notifying a push gateway, present in a SIP path between the SIP User Agent and the SIP network, that the SIP User Agent is registered with the Push Provider, the push gateway having an interface to a push server of the Push Provider. The method further comprises performing initial SIP registration of the SIP User Agent with the SIP network via a SIP connection extending through the push gateway and thereafter maintaining a re-registration timer at the push gateway and, upon or prior to expiry of the timer, sending a push notification identifying a re-registration event from the push gateway to the client device via the push server. The push notification is received at the client device which passes the event notification to the SIP User Agent.

Abstract: A method of maintaining SIP registration in a SIP network for a SIP User Agent resident on a client device, the SIP User Agent having registered with a Push Provider to receive Push Notifications via an Operating System of the client device. The method comprises notifying a push gateway, present in a SIP path between the SIP User Agent and the SIP network, that the SIP User Agent is registered with the Push Provider, the push gateway having an interface to a push server of the Push Provider. The method further comprises performing initial SIP registration of the SIP User Agent with the SIP network via a SIP connection extending through the push gateway and thereafter maintaining a re-registration timer at the push gateway and, upon or prior to expiry of the timer, sending a push notification identifying a re-registration event from the push gateway to the client device via the push server. The push notification is received at the client device which passes the event notification to the SIP User Agent.

Abstract: A mechanism is presented for performing a session transfer with Single Radio Voice Call Continuity, SRVCC, from a Packet Switched, PS, access to a Circuit Switched, CS, access of a telecommunications session that has been established over the PS access via an IP Multimedia Subsystem, IMS, network. The method includes receiving a request for the transfer of the session to the CS access. An indication of an already-seized media gateway, MGW, that has been established for use in one or more other sessions over the CS access is obtained from the IMS network. A MGW is selected as a Mobile-Media Gateway, M-MGW, for the session based on the obtained indication. Allocation of resources for the session in the CS access network is initiated, including specifying the MGW to be used as the Mobile-Media Gateway, M-MGW. Transfer of the session to the CS access is then initiated.

Abstract: A signalling proxy system for a switching center server is provided, as well as a method of operating a signalling proxy system for a switching center server. The signalling proxy system comprises two signalling proxies for routing signalling traffic between a network node and a plurality of switching center server units. Each signalling proxy is addressable by an address code and is operable in one of an active state and a passive state towards the network node.

Abstract: A mechanism is presented for performing a session transfer with Single Radio Voice Call Continuity, SRVCC, from a Packet Switched, PS, access to a Circuit Switched, CS, access of a telecommunications session that has been established over the PS access via an IP Multimedia Subsystem, IMS, network. The method includes receiving a request for the transfer of the session to the CS access. An indication of an already-seized media gateway, MGW, that has been established for use in one or more other sessions over the CS access is obtained from the IMS network. A MGW is selected as a Mobile-Media Gateway, M-MGW, for the session based on the obtained indication. Allocation of resources for the session in the CS access network is initiated, including specifying the MGW to be used as the Mobile-Media Gateway, M-MGW. Transfer of the session to the CS access is then initiated.

Abstract: Apparatus configured to operate within a communication network as a pool proxy, routing signalling traffic between a node of a first network and one of a set of pooled nodes within a second network. The apparatus is further configured to operate in one of an active state and a passive state towards the first network node and, when in said active state to send a heartbeat signal to at least one of said pooled nodes for relaying to a peer pool proxy and, when in said passive state, to receive a heartbeat signal from a peer pool proxy relayed via at least one of said pooled nodes. In the event that no heartbeat signal is received when in the passive state, the apparatus is configured to activate itself as pool proxy towards the first network node.

Abstract: A method and apparatus for managing Time Division Multiplex resources for a pool of Mobile Switching Center Servers in a communications network. Time Division Multiplex resources are provided at a Media Gateway function serving the pool of Mobile Switching Center Servers. Virtual Time Division Multiplex resources are allocated to each Mobile Switching Center Server in the pool and mapped to the Time Division Multiplex resources. An ISUP signalling proxy function may be provided at the Media Gateway function. TDM resources are allocated to at least one Mobile Switching Center, and associated with an identifier of the Mobile Switching Center Server. The TDM resources are mapped to the Time Division Multiplex resource identifier. When the media Gateway receives an ISUP message, it replaces the identifier with an ISDN User Part signalling proxy function identifier before sending the message to a node in an external network.

Abstract: Apparatus configured to operate within a communication network as a pool proxy, routing signalling traffic between a node of a first network and one of a set of pooled nodes within a second network. The apparatus is further configured to operate in one of an active state and a passive state towards the first network node and, when in said active state to send a heartbeat signal to at least one of said pooled nodes for relaying to a peer pool proxy and, when in said passive state, to receive a heartbeat signal from a peer pool proxy relayed via at least one of said pooled nodes. In the event that no heartbeat signal is received when in the passive state, the apparatus is configured to activate itself as pool proxy towards the first network node.

Abstract: A signalling proxy system for a switching center server is provided, as well as a method of operating a signalling proxy system for a switching center server. The signalling proxy system comprises two signalling proxies for routing signalling traffic between a network node and a plurality of switching center server units. Each signalling proxy is addressable by an address code and is operable in one of an active state and a passive state towards the network node.

Abstract: A method and apparatus for managing Time Division Multiplex resources for a pool of Mobile Switching Centre Servers in a communications network. Time Division Multiplex resources are provided at a Media Gateway function serving the pool of Mobile Switching Centre Servers. Virtual Time Division Multiplex resources are allocated to each Mobile Switching Centre Server in the pool and mapped to the Time Division Multiplex resources. An ISUP signalling proxy function may be provided at the Media Gateway function. TDM resources are allocated to at least one Mobile Switching Centre, and associated with an identifier of the Mobile Switching Centre Server. The TDM resources are mapped to the Time Division Multiplex resource identifier. When the media Gateway receives an ISUP message, it replaces the identifier with an ISDN User Part signalling proxy function identifier before sending the message to a node in an external network.