This TR investigates the SIP signalling interworking between entities of IM CN subsystems behaving as specified in the 3GPP profile of SIP and SDP in TS 24.229
, with related call flow examples in TS 24.228
, and SIP network entities external to the IM CN subsystems, which may not adhere to the 3GPP profile of SIP and SDP.
This TR assumes that GPRS access and service based local policy using the Go interface is applied.
Non-GPRS access to IMS may have implications on the TR, which are not yet discussed.