P.3 Inter-system change between A/Gb mode and Iu mode

24.0083GPPCore network protocolsMobile radio interface Layer 3 specificationRelease 18Stage 3TS

An MS is required to perform routing area updating for IMS voice termination if:

1) the upper layers have indicated that the MS is available for voice calls in the IMS (see 3GPP TS 24.301 [120], subclause 3.1);

2) the MS is enabled for mobility management for IMS voice termination;

3) the "IMS voice over PS session indicator" received for Iu mode has the value "IMS voice over PS session supported in Iu mode, but not supported in A/Gb mode"; and

4) the voice domain preference for UTRAN as defined in 3GPP TS 24.167 [134] is not "CS voice only".