A.8 Signalling flows for collaborative session of participants of different subscriptions
24.3373GPPIP Multimedia (IM) Core Network (CN) subsystem IP Multimedia Subsystem (IMS) inter-UE transferRelease 17Stage 3TS
A.8.1 Introduction
This subclause demonstrates the flows for collaborative sessions of participants of diffierent subscriptions.
A.8.2 Signalling flow for controller UE initiated media transfer from controller UE to controllee UE belonging to different subscriptions under the same operator
In the example flow of figure A.8.2-1, UE-1 has an ongoing multimedia session with UE-3 anchored at SCC AS-1. UE-1 and UE-2 belong to different subscribers. UE-1 decides to transfer video media to UE-2 and keep the collaborative session control.
Figure A.8.2-1: Signalling flow for controller UE initiated media transfer from controller UE to controllee UE belonging to different subscriptions under the same operator
NOTE: For clarity, the SIP 100 (Trying) responses are not shown in the signalling flow.
1. UE-1 is in session with UE-3
There is a multimedia session comprising audio and video media between UE-1 and remote UE-3 anchored at SCC AS-1.
2. UE-1 decides to transfer the video portion of the session from UE-1 to UE-2 and keep the collaborative session control.
3-4. SIP REFER request (UE-1 to SCC AS-1) – see example in table A.8.2-3
UE-1 sends a SIP REFER request to SCC AS-1 to request the media transfer.
Table A.8.2-3: SIP REFER request (UE-1 to SCC AS-1)
REFER sip:interUEtransfer@example.net SIP/2.0
Refer-To: <sip:user2@home1.net;gr=urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6?body= m%3Daudio%200%20RTP%2FAVP%97%0Dm%3Dvideo%203002%20RTP%2FAVP%2098%2099>
Via: SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp;branch=z9hG4bKnashds7dfdsdq
Max-Forwards: 70
P-Preferred-Identity: <sip:user1@home1.net>
From: <sip:user1@home1.net>;tag=171828
To: <sip:user2@home1.net;gr=urn:uuid:f81d4fae-7dec-11d0-2222-222222222222>
Call-ID: Asdasd23123366
Cseq: 4897924 REFER
Contact: <sip:user1@home1.net;gr=urn:uuid:f81d4fae-7dec-11d0-1111-111111111111>
Referred-by: sip:user1@home1.net
Accept-Contact:* ;+g.3gpp.iut-focus;explicit;require
Accept: application/sdp, message/sipfrag
Allow: INVITE, ACK, CANCEL, BYE, PRACK, UPDATE, REFER, MESSAGE
Content-Length: 0
5. When SCC AS-1 receives the SIP REFER request, SCC AS-1 authorizes the request.
6-7. SIP 200 (OK) response to SIP REFER request (SCC AS-1 to UE-1).
8-9. SIP NOTIFY request (SCC AS-1 to UE-1)
SCC AS-1 informs UE-1 about the implicit subscription to the SIP REFER request results.
10-11. SIP 200 (OK) response to SIP NOTIFY request (UE-1 to SCC AS-1)
UE-1 confirms the SIP NOTIFY request by sending a SIP 200 (OK) response to the SIP NOTIFY request.
12-15. SIP INVITE request (SCC AS-1 to UE-2) – see example in table A.8.2-12
SCC AS-1 sends the SIP INVITE request towards UE-2 to establish a session based on the information provided in the SIP REFER request.
Table A.8.2-12: SIP INVITE request (SCC AS-1 to UE-2)
INVITE sip:user2@home2.net SIP/2.0
Via: SIP/2.0/UDP
Max-Forwards:
From: <sip:interUEtransfer@example.net>;tag=38789
To: <sip:user2@home2.net; >
Call-ID: duie4hr3896
Cseq: 41 INVITE
Contact: <sip:sccas1.home1.example.net>;+g.3gpp.iut-focus
Referred-By: sip:user1@home1.net
Allow: INVITE, ACK, CANCEL, BYE, PRACK, UPDATE, REFER, MESSAGE
Content-Type: application/sdp
Content-Length: (…)
v=0
o=- 1027933615 1027933615 IN IP4 123.112.67.87
s=-
c=IN IP4 123.112.67.87
t=0 0
m=audio 0 RTP/AVP 97
m=video 3002 RTP/AVP 98 99
b=AS:75
a=rtpmap:98 H263
a=fmtp:98 profile-level-id=0
a=rtpmap:99 MP4V-ES
16-19. SIP 200 (OK) response to SIP INVITE request (UE-2 to SCC AS-1)
UE-2 acknowledges the SIP INVITE request by sending a SIP 200 (OK) response to SCC AS-1.
20-23. SIP ACK request (SCC AS-1 to UE-2)
SCC AS-1 sends a SIP ACK request to UE-2.
24-25. SIP re-INVITE request (SCC AS-1 to UE-1)
SCC AS-1 sends a SIP re-INVITE request to UE-1 to hold the media to be transferred.
26-27. SIP 200 (OK) response (UE-1 to SCC AS-1)
UE-1 acknowledges the SIP re-INVITE request by sending a SIP 200 (OK) response to SCC AS-1.
28-29. SIP ACK request (SCC AS-1 to UE-1)
SCC AS sends a SIP ACK request to UE-1.
30-32. SIP re-INVITE request (SCC AS-1 to UE-3)- see example in table A.8.2-30
SCC AS-1 sends a SIP re-INVITE request to the remote UE to update the video media.
Table A.8.2-30: SIP INVITE request (SCC AS-1 to UE-3)
INVITE sip:user3@home3.net SIP/2.0
Via:
To: sip:user3_public3@home3.net;tag = 66666
From: sip:interUEtransfer@example.net; tag=33333
Call-ID:
CSeq:
Max-Forwards:
P-Asserted-Identity:
Require:
Contact: sip:user1@home1.net;gr=urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91ewxyz
Allow:
Content-Type: application/sdp
Content-Length: (…)
v=0
o=- 1027933615 1027933615 IN IP4 123.45.67.89
s=-
t=0 0
m=audio 1300 RTP/AVP 96 97
c=IN IP4 123.45.67.89
b=AS:25.4
a=rtpmap:96 AMR
a=fmtp:96 mode-set=0,2,5,7; mode-change-period=2
a=rtpmap:97 telephone-event
a=maxptime:20
m=video 1302 RTP/AVP 98 99
c=IN IP4 145.23.77.88
b=AS:75
a=rtpmap:98 H263
a=fmtp:98 profile-level-id=0
a=rtpmap:99 MP4V-ES
33-35. SIP 200 (OK) response to re-INVITE request (UE-3 to SCC AS-1)
After successful media update, UE-3 sends a SIP 200 (OK) response towards SCC AS-1.
36-38. SIP ACK request (SCC AS-1 to UE-3)
SCC AS-1 sends a SIP ACK request to remote UE-3.
39-40. SIP re-INVITE request (SCC AS-1 to UE-1)
The SCC AS sends a SIP re-INVITE request to UE-1 to update the media in UE-1.
41-42. SIP 200 (OK) response (UE-1 to SCC AS-1)
UE-1 acknowledges the SIP re-INVITE request by sending a SIP 200 (OK) response to SCC AS-1.
43-44. SIP ACK request (SCC AS-1 to UE-1)
The SCC AS sends a SIP ACK request to UE-1.
45-48. SIP re-INVITE request (SCC AS-1 to UE-2)
SCC AS-1 sends a SIP re-INVITE request to UE-2 to activate the video media components.
49-52. SIP 200 (OK) response (UE-2 to SCC AS-1)
UE-2 acknowledges the SIP INVITE request by sending a SIP 200 (OK) response to the SCC AS.
53-56. SIP ACK request (SCC AS-1 to UE-2)
The SCC AS sends a SIP ACK request to UE-2.
57-58. SIP NOTIFY request (SCC AS-1 to UE-1)
SCC AS-1 informs the UE-1 that the action triggered by the SIP REFER request was successfully completed.
59-60. SIP 200 (OK) response to SIP NOTIFY request (UE-1 to SCC AS-1)
UE-1 confirms the SIP NOTIFY request by sending a SIP 200 (OK) response to the SIP NOTIFY request.