On 5/23/18 1:34 PM, Abhishek wrote:
Hello Paul,
Thank you very much for response.
We could see with some of the peer nodes that Call is continuing even if ACK
message does not carry SDP.
Behavior after a protocol violation is undefined, so if they want to try
to go forward in that case they can. But the state of the session is
undefined in that case.
Thanks,
Paul
Best Regards,
Abhishek Phadke
On 23-May-2018, at 22:38, Paul Kyzivat <pkyzi...@alum.mit.edu> wrote:
Abhishek,
On 5/23/18 7:15 AM, Abhishek wrote:
Hello,
SS7 Switch —> Gateway Switch —> SIP SBC
Call flow is as mentioned.
SIP call gets established between Gateway Switch node and SIP SBC node.
Gateway Switch node initiates Re Invite without SDP.
SIP SBC node responds with 200 OK along with SDP keeping all fields same as
previous 200 OK including ‘sess-version’ field.
Gateway Switch node acknowledge this message with ACK without SDP.
SIP SBC node sends BYE to this response and mentions Reason as cause=488, No
answer to offer.
Would like to understand way forward for resolution of this issue.
While the details are sketchy, IIUC then the Gateway Switch is clearly in error
- it is required to include answer SDP in the ACK.
Thanks,
Paul
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