I'm using FreePBX with Grandstream phones. I have FreePBX configured to allow Listen *222ext#, Whisper *223ext#, and Barge *224ext#.
All I have to do is dial *222 plus the extension and I can Listen in on a call. Works great.
My problem is we just purchased Cisco SPA303 phones. When I dial *222ext# as soon as the second 2 is dialed I get Address Incomplete.
Does anyone know how to get this working on these Cisco phones.