When an incoming call through the trunk, DTMF does not work, even in the console are not displayed. In Asterisk, everything worked. Type DTMF put rf2833 as standing on Aster. On the internal rooms everything works. In addition, if you run start_dtmf and then bridge, and wait until the called subscriber picks up the DTMF start to work, even if the subscriber immediately after answering drops the call.

What can be wrong?

  • Found another crutch. If after the application answer perform any playback application. DTMF is also starting to work as expected. - Vladimir
  • No, they still work with such a crutch once. - Vladimir

1 answer 1

Registration DTMF in FreeSWITCH is possible only after answering the call. Then you need to give the answer command in the start_dtmf before start_dtmf .

In practice, FreeSWITCH believes that from an unanswered call, it simply cannot receive DTMF signals (no media session is established)

There is a subtle nuance connected with the fact that theoretically in the telephone network (SIP or not - it does not matter) there is a two-way audio transmission mode without an answer (for SIP without sending a packet with code 200 OK), but in practice I have not met a single operator which would support this, so the requirement of a response in FreeSWITCH for registering DTMF is quite consistent with reality.