PSTN call transfers and callpark on a Become silent after in a direct routing environment.

[T_admin865]

Hello Teams Community,

Please I need your help on this.

PSTN call transfers and callpark on a Become silent after in a direct routing environment.

■ About the event that is occurring:
-When an incoming / outgoing call via direct routing is transferred to another user in Teams, it becomes silent.
-Call flow
1. Call Teams-userXX from an outside line.
2. Respond with Teams-userXX (at this point the voice can be heard in both directions).
3. "Cold transfer (without consultation)" Teams-UserXX to Teams-userYY.
4. Answer the call transferred Teams-userYY (silence in both directions).
* Similarly, the call park will be silent in both.

In the case of "consultation (warm transfer)", it works.

[#2]

Are you using direct routing, or calling plans? I've seen this happen in direct routing environments where the reINVITE message is being sent, and one side doesn't support it. Depending on the SBC, there is usually some good documentation on configurations for Teams setup. For example AudioCodes has a document that walks through all the appropriate settings for their SBC line.

*EDIT* I should have read a little closer, I do see you're using direct routing.  I'd double check the configurations for handling reINVITE messages.  For example, AudioCodes suggest having it configured to "handle locally", which I think believe the SBC from telling Teams that it supports it, and helps with this issue.