Call Transfer: Using SIP REFER
Microsoft Teams does not naturally send a REFER message to your PBX when a call is transferred or parked. This causes broken SIP flows or incomplete information for normal processing. To use REFER you must opt in to that functionality on each direct route.
.png?sv=2022-11-02&spr=https&st=2025-06-27T21%3A07%3A40Z&se=2025-06-27T21%3A18%3A40Z&sr=c&sp=r&sig=LUe7ARNPVWCgB%2Fsy40x6kMRPv7GMzoEQK2SnKLlAVaM%3D "image(222).png")
Benefits of enabling REFER:
Call parking and transferring will work as is typical.
Drawbacks of enabling REFER:
Attended transfers will not work unless the PBX hairpins the transferred call back to Teams where the media is anchored.
The only supported codec is G.711
In Netsapiens versions earlier than v43.2, there is a known compatibility issue with Netsapiens and Microsoft with transfers. Netsapiens does not send a NOTIFY to let Microsoft know the status of the transfer; it sends a BYE instead. The Netsapiens workaround is to NOT enable REFER in the ConnecttoTeams portal; this lets ConnecttoTeams' SBC handle processing of the REFER instead of asking the PBX to handle it (incorrectly).