>
> A —> Switch —> B
> All 3 nodes connected with SIP connectivity.
> A sending INVITE to B but does not contain Require:100REL. Switch forwards
> Invite to B but has Require:100REL.
> B responds with 180 without SDP, Switch forwards the same to A. B then
> sends 183+SDP, which switch sends to A. Then A sends 200OK which Switch
> does not forward to A. B sends 200OK multiple times as per standard and
> Switch disconnects session at both the ends with SIP cause code 500.
>
Hi.
I tried to visualize the call flow:
A Switch B
+-----------> +---------->
INVITE INVITE
Require: 100rel
<-----------+ <----------+
180 w/o SDP 180 w/o SDP
<-----------+ <----------+
183 w/ SDP 183 w/ SDP
<----------+
200 OK
<----------+
200 OK
[...]
Your described call flow lacks some details:
1. Does the INVITE contain any SDP?
2. Was the INVITE from Switch to B really send with Require: 100rel?
3. Are there any other SIP-Requests containing either "Supported: 100rel"
or "Required: 100rel"?
4. Were there any PRACK-Requests send?
5. Does the 200 OK contain any SDP?
BR
Philipp
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