Three party conference call fails

Super Contributor

Hello Teams Community,


Please I need your help on this issue.


Customer Locala is using Direct Routing. Session border controller using is AudioCodes SBC. Last 1 week, end-users when they are doing three-party calls, the third call is never pushed to the SBC.
The User (ADVTEST.) once the call is established with Party A, presses people in the call, and the participant window shows up.
Here they try the Party B number. Teams make a conference call. Once the conference call is started, all caller could here is party B is leaving.
He could briefly see that called number B is leaving. He called B number receives the call.
Please see the screen shot.


On the Call history details we can see the call is originated by Teams.
This was working two weeks ago before and suddenly this type of 3rd party ( external) call initiation fails. 
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