We link the AudioCodes SBC with MS Direct Routing, and link the SBC with our internal PBX phone system, now we're able to call from teams client to internal extension or call via PSTN to external user.
but now we have question on audio conference call, for example:
1. User A is making teams phone call with user B,
2. Next, user A invite user C to join the call, user C is unable to join if A dial the office extension of C,
3. it works when A dial the external DID number of C.
All A, B, C users are using E5 licenses.
Why have such problem, from my understanding User A could invite 3 party users to conference via the DID number, then mean the SBC passed the call to the PBX and reach the user C via the PSTN, why cannot invite user C's extension to join the conference? any setting issue on PBX or MS side?
