When using Asterisk to dial into a SIP provider, leaving dtmfmode as rfc2833 for that SIP ‘friend’ enables DTMF to be recognized by the SIP provider. Using a Dial(SIP/XX|10|t) should enable transfers on the SIP provider’s side, but Asterisk does not recognize the DTMF thats required to initiate transfers when using dtmfmode=rfc2833.
When I switch to inband in sip.conf, Asterisk now recognizes the DTMF and initiates the transfer but the DTMF no longer get passed to the SIP provider.
I have tried INFo and AUTO dtmfmode, and have not had luck getting DTMFs to be recognized both ways.
Is there a way to pass DTMFs through Asterisk from the callee and called side?