Section: 4.3.2.4 Change or determination of IMS registration status
Content: Whenever the UE's availability for voice calls in the IMS is determined or changes (e.g. whenever the IMS registration status is determined or changes), the UE dependent on its mode of operation shall execute procedures according to table 4.3.2.4.1, 4.3.2.4.2 or 4.3.2.4.3: a) The UE is operating in PS mode 1 Table 4.3.2.4.1: Change of IMS registration status for a UE in PS mode 1 NOTE 1: If the UE in PS mode 1 transits to CS/PS mode 1 according to table 4.3.2.4.1, then the UE can return to PS mode 1 when the upper layer indicates the status of being available for voice over PS. b) The UE is operating in PS mode 2 Table 4.3.2.4.2: Change of IMS registration status for a UE in PS mode 2 NOTE 2: If the UE in PS mode 2 transits to CS/PS mode 2 according to table 4.3.2.4.2, then the UE can return to PS mode 2 when the upper layer indicates the status of being available for voice over PS. c) The UE is operating in CS/PS mode 1 Table 4.3.2.4.3: Change of IMS registration status for a UE in CS/PS mode 1