Patent ID: 8885603

Claim:
A method of 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 comprising: receiving a request for the transfer of the session, wherein the request includes information regarding a plurality of supported codecs; obtaining from the IMS network an indication of a voice codec that is currently being used for the session, wherein the indicated voice codec that is currently being used for the session is one of the plurality of supported codecs; initiating allocation of resources for the session in the CS access, including specifying the voice codec to be used based on the obtained codec indication; and initiating transfer of the session to the CS access so that the session continues with use of the specified voice codec.