Abstract: A method of notifying one or more network nodes in a communications network, comprising an Internet Protocol Multimedia Subsystem, IMS, of a change in RAT used by a user equipment for a communications session, the method comprising at a CSCF prior to set-up of the communications session, indicating by the CSCF to a PCRF that the CSCF requires RAT change notifications for the user equipment, providing a capability indication by the CSCF to the one or more network nodes that the CSCF supports RAT change notifications and receiving from at least one of the one or more network nodes a requirement indication, which indicates that the network node requires RAT change notifications. The method further comprises on receipt of a RAT change notification by the CSCF propagating the RAT change notification to each of the nodes from which a requirement indication has been received.

Abstract: A method of notifying one or more network nodes in a communications network, comprising an Internet Protocol Multimedia Subsystem, IMS, of a change in RAT used by a user equipment for a communications session, the method comprising at a CSCF prior to set-up of the communications session, indicating by the CSCF to a PCRF that the CSCF requires RAT change notifications for the user equipment, providing a capability indication by the CSCF to the one or more network nodes that the CSCF supports RAT change notifications and receiving from at least one of the one or more network nodes a requirement indication, which indicates that the network node requires RAT change notifications. The method further comprises on receipt of a RAT change notification by the CSCF propagating the RAT change notification to each of the nodes from which a requirement indication has been received.

Abstract: A method of maintaining cached Session Initiation Protocol (SIP) terminal capability information at an end user terminal of a telecommunication system, for one or more other end user terminals. The method comprises predefining one or more signalling message properties for signalling messages to be received from peer terminals, and recording the properties at said end user terminal, examining incoming signalling messages received from peer terminals to determine whether or not they possess a predefined property, and if an incoming signalling message does possess a predefined property, reacting by refreshing the cached capability information for the sending terminal.

Abstract: A method of maintaining cached Session Initiation Protocol (SIP) terminal capability information at an end user terminal of a telecommunication system, for one or more other end user terminals. The method comprises predefining one or more signalling message properties for signalling messages to be received from peer terminals, and recording the properties at said end user terminal, examining incoming signalling messages received from peer terminals to determine whether or not they possess a predefined property, and if an incoming signalling message does possess a predefined property, reacting by refreshing the cached capability information for the sending terminal.