1. Title: eDRVCC requirement and method Source: China Telecom Abstract:
3GPP2 SX xx
TSG-SX WG2 -MMD
Title: eDRVCC requirement and method
Source: China Telecom
Abstract:
This contribution provides the requirement for eDRVCC and some possible method to support the call transfer from PS to CS.
Recommendation:
Discussion and decision for eDRVCC WI.
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2. Overview of 3GPP2 VCC present specification
Outline
Overview of 3GPP2 VCC present specification
Service and network requirement for eDRVCC
possible method to support the call transfer from PS to CS in 3GPP2 network

3. Overview of 3GPP2 VCC present specification
X.S
Initial Version, basic call transfer from PS(WLAN, HRPD) to 1x is specified.
Supplementary services and call intermediate state is not addressed.
X.S0042-A 1.0
DRVCC and SRVCC procedure are classfied.
X.S0042-B 1.0
IMS Emergency Call for DRVCC is specified.
X.P0042-C 1.0
IMS regular and Emergency Call for SRVCC will be specified.

4. Service and network requirement for eDRVCC
Service requirement
DRVCC Call transfer from PS to CS on call intermediate state
outgoing call in alerting state
incoming call in alerting state
DRVCC Call transfer from PS to CS for supplementary services which include more than one session
call waiting
call hold
3WC
Network requirement
To 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.

5. possible method to support the eDRVCC call transfer
Call transfer from PS to CS on call alerting state
reference to 3GPP , outgoing call in alerting state for DRVCC 90
UE 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

6. reference to 3GPP 23.237, incoming call in alerting state for DRVCC
At step 6, UE init transfer request through Gm inferface to SCC AS

7. possible method to support the eDRVCC call transfer
Call transfer from PS to CS for supplementary services
3GPP should not be referenced, because in MSC must be enhanced to support mid-call or ICS for transfering the rest sessions
Possible method for support more than one session transfer
UE 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.

8. possible procedure for call transfer in call waiting state
UE initiate one session transfer, then SCC AS initiate another session transfer