AASBC: SBC Not Accepting Shuffling Re-invite With No SDP


Doc ID    SOLN295138
Version:    6.0
Status:    Published
Published date:    26 Oct 2021
Created Date:    19 Aug 2016
Author:   
Nilesh Yadav
 

Details

 AASBC all versions

 

Problem Clarification

Unable to establish a call from SIP phone. Call end in 3 seconds. Called Party has answered the call but there was no talk path, he hanged up. Caller has seen the call timer counting, but has not heared anything once the call has been established.

 Call Flow : Station -> SM -> CM -> SM -> SBC  ->  SIP Trunk

Carrier is sending 180 after 183

Cause

 During investigation got to know CM sending Re-Invite to shuffle the call to SM. Shuffling re invite has no SDP. SM is sending same re-invite to SBC. SBC should not be sending it to service provider (SP). However it was forwarding it SP. 

 SBC was not processing re invite with no SDP correctly

Solution

Configuration change in SBC  

Global Profiles – Server Interworking – SIP_BT  -> Delayed SDP Handling    Yes 

Also refer to SOLN334364 - Communication Manager:Enable special application (SA8965) - SIP Shuffling with SDP?

Additional Relevant Phrases

Delayed SDP handling, oneway audio for transferred call to PSTN

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