Hi All, I'm trying to get DTMF to work though the Sip Proxy Manager/Tunnel connection. Setup: v10 SP5 (build 22686), Grandstream 4104 PSTN Gateway Internal Phones: Aastra 480i External Phones: GrandStream GXP2110, 3CX Softphone DTMF works from the internal phones fine, but not from the GrandStream or from the softphone. What's strange is that dialing voicemail and entering the pin works through the SPM/tunnel connection, but in-call DTMF to "outside" parties doesn't. Since the internal phones work it doesn't seem to me to be a configuration issue with the PSTN gateway, but I have to confess I don't know where to look. The only thing I can see in the logs is this: MediaServer|MediaServerReporting:TMFhandler:[MS211000] C:16.1: http://www.xxx.yyy.zzz:10016 is delivering DTMF using RTP payload (RFC2833). In-Band DTMF tone detection is disabled for this call segment. Both the GrandStream and the Softphone are set to RFC2833 DTMF with "Payload Number" set to 101, which matches the DTMF payload type in the PSTN gateway. Any suggestions or pointers are much appreciated! Rgds - M.