PSTN Call transfer ends call - Direct Routing

New Contributor

Currently running Ribbon SBC 2K setup for Teams direct routing.


If Party A (external caller) calls Party B (Teams user) and Party B attempts to transfer the call, the call in Teams drops / ends, before any number is dialled (Transfer keypad appears for approx 1 second).  Party A call remains up.

However in the reverse, if Party B (Teams user) calls party A (external caller), the call can be transferred.  The transfer dialogue remains open so a number can be inserted.

Teams client and Ribbon SBC all at latest versions and any calls placed on hold can be resumed without incident.

2 Replies
Do you have a copy of the SIP trace in both directions? I've seen similar when a SIP INVITE is sent to Teams during the middle of a call, causing Teams to drop the call.
best response confirmed by daveaus (New Contributor)


That was the really strang part.  I wasn't receiving any INVITE, REINVITE or even BYE.  The call would stay up as far as SBC is concerned.  Anyway I Enabled Hold Music on Teams SG on the Ribbon SBC.  This has fixed the issue even though calls on hold were never at fault.

Thanks for the response though!