Asterisk not receiving dtmf on incoming calls from simple phones

Hi,

Am using sip trunking and auto for dtmfmode and Asterisk is able to receive dtmf for Smartphones on both incoming and outgoing calls. But on a simple phone, Asterisk 16 is only able to receive dtmf on incoming calls and not on outgoing calls. I saw this in the link below “For analog lines, inband audio is the only possible means to transmit DTMF.”

Does this mean that Asterisk can only receive dtmf from simple phone on incoming calls only?

Asterisk has no concept of simple versus smart phones. My best guess is that a smartphone really means a SIP application running on a smartphone rather than the standard telephone app.

You should normally user rfc2833 (RFC 4733) over SIP trunks, but you should discuss this with the people at the other end of the trunk.

You need to look at the whole system, rather than just Asterisk, although I would suggest that dtmfmode=rfc2833 is the most likely one to get the whole system to work.

Thanks for the clarification.
I notice that i was actually using rfc2833 as the dtmf mode. My SIP provider normally will require auto, so i now use auto for dtmf mode and it all working fine.
Thanks