A.25 Video Conference Creation / 5GS
34.229-53GPPInternet Protocol (IP) multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP)Part 5: Protocol conformance specification using 5G System (5GS)Release 16TSUser Equipment (UE) conformance specification
Expected sequence
|
Step |
Direction |
Message |
Comment |
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|
UE |
SS |
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|
1 |
🡪 |
INVITE |
UE sends INVITE with the first SDP offer. |
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|
2 |
🡨 |
100 Trying |
SS sends a 100 Trying provisional response. |
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|
3 |
🡨 |
183 Session Progress |
SS sends an SDP answer. |
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|
4 |
🡪 |
PRACK |
UE acknowledges reception of 183 Session Progress., with optional SDP offer |
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|
5 |
🡨 |
200 OK |
SS responds to PRACK. |
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|
Exception : Step 6-7 describe optional behaviour depending on UE implementation. The steps will be executed if no SDP offer was included in PRACK at step 4 |
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|
6 |
🡪 |
UPDATE |
UE sends a second SDP offer in an UPDATE request. |
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|
7 |
🡨 |
200 OK |
SS responds to UPDATE. |
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|
8 |
<- |
200 OK |
The SS responds INVITE with 200 OK and gives the final conference URI within the response |
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|
9 |
-> |
ACK |
The UE acknowledges the receipt of 200 OK for INVITE |
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|
EXCEPTION: steps 10–13 describe optional behaviour depending on UE configuration. The SS shall wait up to 3s for the SUBSCRIBE of step 10 |
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|
10 |
-> |
SUBSCRIBE |
UE subscribes the conference event |
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|
11 |
<- |
200 OK |
SS responds to the subscription |
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|
12 |
<- |
NOTIFY |
SS sends the initial state of the conference event to the UE |
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|
13 |
-> |
200 OK |
UE responds to the NOTIFY |
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Specific Message Contents
The specific message contents for steps 1–7 is otherwise identical to what have been specified in Annex A.15.1, but with the exceptions as below:
INVITE (Step 1)
|
Header/param |
Value/remark |
|---|---|
|
Request-Line |
|
|
Request-URI |
sip:mmtel@conf-factory appended with px_IMS_HomeDomainName |
|
To |
|
|
addr-spec |
sip:mmtel@conf-factory appended with px_IMS_HomeDomainName |
183 Session in Progress for INVITE (Step 3)
|
Header/param |
Value/remark |
|---|---|
|
Contact |
|
|
addr-spec |
sip:temporary@conf-factory. appended with px_IMS_HomeDomainName |
|
feature-param |
isfocus |
|
Record-Route |
|
|
rec-route |
<sip:SS P-CSCF address: protected server port of SS;lr> |
PRACK (Step 4)
|
Header/param |
Value/remark |
|---|---|
|
Require |
(present, if Message-Body is present) |
|
option-tag |
precondition |
|
Message-body |
(if present, shall be the same as message body in UPDATE at step 6 of Annex A.15.1) |
200 OK for PRACK (Step 5)
|
Header/param |
Value/remark |
|---|---|
|
Require |
(present, if Message-Body is present) |
|
option-tag |
precondition |
|
Content-Type |
|
|
media-type |
(present, if SDP message-Body was present in PRACK at step 4) |
|
application/sdp |
|
|
Content-Length |
(present if SDP message-Body was present in PRACK at step 4) |
|
value |
length of message body |
|
Message-body |
(present, if SDP message-Body was present in PRACK at step 4) same as message body in 200 OK for UPDATE at step 7 of Annex A.15.1 |
200 OK for INVITE (Step 8)
Use the default message “200 OK for other requests than REGISTER or SUBSCRIBE” in Annex A.3.1 of TS 34.229-1 [2], applying conditions A1 and A5 with the following exceptions:
|
Header/param |
Value/remark |
|---|---|
|
Record-Route |
|
|
rec-route |
Same value as in the 183 response |
|
Contact |
|
|
addr-spec |
sip:final@conf-factory. appended with px_IMS_HomeDomainName |
|
feature-param |
Isfocus |
ACK (Step 9)
Use the default message “ACK” in Annex A.2.7 of TS 34.229-1 [2], applying conditions A1 and A3, with the following exceptions:
|
Header/param |
Value/remark |
|---|---|
|
Request-Line |
|
|
Request-URI |
sip:final@conf-factory. appended with px_IMS_HomeDomainName |
SUBSCRIBE (Step 10)
Use the default message “SUBSCRIBE for conference event package” in Annex A.5.1 of TS 34.229-1 [2], applying conditions A1 and A7.
200 OK (Step 11)
Use the default message “200 OK for SUBSCRIBE” in Annex A.5.2 of TS 34.229-1 [2], applying condition A1.
NOTIFY (Step 12)
Use the default message “MT NOTIFY for conference event package” in Annex A.5.3 of TS 34.229-1 [2], applying condition A5.
200 OK (Step 13)
Use the default message “200 OK for other requests than REGISTER or SUBSCRIBE” in Annex A.3.1 of TS 34.229-1 [2], applying conditions A5 and A22.