Section: P.5 Inter-system change between Iu mode and S1 mode
Content: An MS is required to perform routing area updating for IMS voice termination at inter-system change from S1 mode to Iu mode and tracking area updating for IMS voice termination at inter-system change from Iu mode to S1 mode if: 1) conditions 1 and 2 of annex P.3 are fulfilled; and 2) any of the following conditions a, b and c is fulfilled: a) the IMS voice over PS session indicators received for Iu mode and S1 mode have the values - "IMS voice over PS session supported in Iu mode, but not supported in A/Gb mode" and - "IMS voice over PS session in S1 mode not supported", and the voice domain preference for UTRAN as defined in 3GPP TS 24.167[ 3GPP IMS Management Object (MO); Stage 3 ]  [134] is not "CS voice only"; b) the IMS voice over PS session indicators received for Iu mode and S1 mode have the values - "IMS voice over PS session in Iu mode and A/G mode not supported" and - "IMS voice over PS session in S1 mode supported", and the voice domain preference for E-UTRAN as defined in 3GPP TS 24.167[ 3GPP IMS Management Object (MO); Stage 3 ]  [134] is not "CS voice only"; or c) the IMS voice over PS session indicators received for Iu mode and S1 mode have the values - "IMS voice over PS session supported in Iu mode, but not supported in A/Gb mode" and - "IMS voice over PS session in S1 mode supported", and exactly one of the voice domain preferences for UTRAN and E-UTRAN as defined in 3GPP TS 24.167[ 3GPP IMS Management Object (MO); Stage 3 ]  [134] is "CS voice only".