2Overview of 3GPP2 VCC present specification OutlineOverview of 3GPP2 VCC present specificationService and network requirement for eDRVCCpossible method to support the call transfer from PS to CS in 3GPP2 network
3Overview of 3GPP2 VCC present specification X.SInitial Version, basic call transfer from PS(WLAN, HRPD) to 1x is specified.Supplementary services and call intermediate state is not addressed.X.S0042-A 1.0DRVCC and SRVCC procedure are classfied.X.S0042-B 1.0IMS Emergency Call for DRVCC is specified.X.P0042-C 1.0IMS regular and Emergency Call for SRVCC will be specified.
4Service and network requirement for eDRVCC Service requirementDRVCC Call transfer from PS to CS on call intermediate stateoutgoing call in alerting stateincoming call in alerting stateDRVCC Call transfer from PS to CS for supplementary services which include more than one sessioncall waitingcall hold3WCNetwork requirementTo support the above service, the MSC can not be enhanced/updated. Just like what is done in present X.S0042, MSC acts as a normal MSC during basic call transfer for DRVCC.
5possible method to support the eDRVCC call transfer Call transfer from PS to CS on call alerting statereference to 3GPP , outgoing call in alerting state for DRVCC90UE and SCC AS cooperate through Gm /Mw interface to finish the alerting call transfer from PS to CS.MSC acts as a normal MSC and move to the correct call state.At step 1, UE initiate transfer action which pass through Mw inferface to SCC AS
6reference to 3GPP 23.237, incoming call in alerting state for DRVCC At step 6, UE init transfer request through Gm inferface to SCC AS
7possible method to support the eDRVCC call transfer Call transfer from PS to CS for supplementary services3GPP should not be referenced, because in MSC must be enhanced to support mid-call or ICS for transfering the rest sessionsPossible method for support more than one session transferUE and SCC AS cooperate through Gm /Mw interface to transfer all the sessions(call legs) one by one. MSC acts as a normal MSC and move to the correct service state during entire sessions transfer.
8possible procedure for call transfer in call waiting state UE initiate one session transfer, then SCC AS initiate another session transfer