Content for TS 24.186 Word version: 18.0.0
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. 41
A.1.3.1 IMS serving the transferee provides data channel service p. 41
A.1.3.1.1 Blind Transfer p. 41
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/MRF 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/MRF 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. 43
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/MRF 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/MRF 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.
