Content for TS 24.186 Word version: 19.0.0
A.1.3 Explicit Communication Transfer
A.1.3.1 IMS serving the transferee provides data channel service
A.1.3.1.1 Blind Transfer
A.1.3.1.2 Consultation Transfer
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A.1.3 Explicit Communication Transfer p. 45
A.1.3.1 IMS serving the transferee provides data channel service p. 45
A.1.3.1.1 Blind Transfer p. 45
Figure A.1.3.1.1-1: Blind Transfer when IMS serving the transferee provides data channel service
(⇒ copy of original 3GPP image)
(⇒ copy of original 3GPP image)
Figure A.1.3.1.1-1 shows a call flow for blind transfer when IMS serving the transferee provides data channel service.
Step 1.
UE-A calls UE-B, UE-A sends an INVITE request towards the UE-B.
Step 2.
DC media resource is allocated by IMS-A for UE-A and UE-B.
Step 3-6.
UE-B answers the call, session connection is established between UE-A and UE-B. IMS-A establishes BDC connection for UE-A and UE-B. And then IMS-A establishes ADC connections between UE-A and UE-B.
Step 7.
UE-B starts transfer process.
Step 8.
UE-B sends a REFER message to transfer the call to UE-C.
Step 9-10.
IMS-B sends 202/NOTIFY to UE-B to accept the transfer request, and then sends BYE message to UE-B.
Step 11-12.
IMS-B sends an INVITE message to UE-C, UE-C replies SDP offer with data channel media in 18X/200 response.
Step 13.
IMS-B sends reINVITE message to IMS-A.
Step 14-16.
IMS AS of IMS-A notifies session modify event to the DCSF and as per media instruction request from the DCSF, the IMS AS sends media resource management request to MF to update the data channel media resources for UE-C.
Step 17-19.
IMS AS of IMS-A sends an reINVITE message carrying SDP offer with data channel media towards UE-A. UE-A replies SDP answer with data channel media in the 200 OK response.
Step 20-22.
IMS AS of IMS-A notifies session modify event to the DCSF and as per media instruction request from the DCSF, the IMS AS sends media resource management request to MF to update the data channel media resources for UE-A.
Step 23.
IMS AS of IMS-A sends a 200 OK message with updated data channel media to IMS-B.
Step 24.
IMS-B sends PRACK/ACK message towards UE-C.
Step 25.
The BDC media connection is established between IMS-A and UE-C.
Step 26.
The ADC media connections are established between UE-A and UE-C.
Step 27.
The session connection is established between UE-A and UE-C.
A.1.3.1.2 Consultation Transfer p. 47
Figure A.1.3.1.2-1: Consultative Transfer when IMS serving the transferee provides data channel service
(⇒ copy of original 3GPP image)
(⇒ copy of original 3GPP image)
Figure A.1.3.1.2-1 shows a call flow for consultative transfer when IMS serving the transferee provides data channel service.
Step 1.
UE-A calls UE-B, UE-A sends an INVITE request towards the UE-B.
Step 2.
DC media resource is allocated by IMS-A for UE-A and UE-B.
Step 3-6.
UE-B answers the call, session connection is established between UE-A and UE-B. IMS-A establishes BDC connection for UE-A and UE-B. And then IMS-A establishes ADC connections between UE-A and UE-B.
Step 7-8.
UE-B holds UE-A, and then calls UE-C.
Step 9.
When UE-C sends 180 ringing or 200 response, UE-B starts transfer process.
Step 10.
UE-B sends a REFER message to transfer the call to UE-C.
Step 11-12.
IMS-B sends 202/NOTIFY to UE-B to accept the transfer request, and then sends BYE message to UE-B.
Step 13-15.
IMS-B sends a media re-negotiation request to UE-A, UE-A replies SDP offer with data channel media description.
Step 16-18.
IMS AS of IMS-A notifies session modify event to the DCSF and as per media instruction request from the DCSF, the IMS AS sends media resource management request to MF to update the data channel media resources for UE-A.
Step 19.
IMS AS sends a 200 OK response for re-INVITE to the IMS-B with updated data channel media.
Step 20-21.
IMS-B sends a re-INVITE message carrying SDP offer with data channel media towards UE-C, and receives 200 OK response for reINVITE carrying SDP answer with data channel media from UE-C.
Step 22.
IMS-B sends an ACK message carrying SDP answer with data channel media towards IMS-A.
Step 23-25.
IMS AS of IMS-A notifies session modify event to the DCSF and as per media instruction request from the DCSF, the IMS AS sends media resource management request to MF to update the data channel media resources for UE-C.
Step 26.
IMS AS of IMS-A sends an ACK message carrying SDP answer with data channel media towards UE-A.
Step 27.
The BDC media connection is established between IMS-A and UE-C.
Step 28.
The ADC media connections are established between UE-A and UE-C.
Step 29.
The session connection is established between UE-A and UE-C.
