DTMFs not recognized on Freeswitch

[krakatoa]

Hi guys, I've compiled the following scenario:

SippyCup::Scenario.new("Test", opts) do |s|
  s.invite
  s.wait_for_answer
  s.ack_answer

  s.sleep 5
  s.send_digits "1"
  s.sleep 20

  s.wait_for_hangup                                                                                                                                                                   
end

Tried it against a Freeswitch (v1.2.15) instance, and it seems FS does not recognize the media into DTMFs. SippyCup is at v0.3.0. FS profile has liberal-dtmf=true.
I've made a SIPp run by using this DTMFs RFC2833 pcaps https://code.osso.nl/projects/sipp/browser/pcap (provided by SIPp), and that way FS did recognize the DTMFs.

[benlangfeld]

@bklang Could you clarify the way SippyCup generates DTMF? Is it 2833?

[bklang]

Yes, the goal is to be RFC2833 compliant. I've not looked at RFC4733 yet, but my understanding is that 4733 is mostly(?) backward compatible.

I would appreciate further information on what liberal-dtmf=true does on FreeSWITCH so I can fix any errors in teh DTMF generation. My guess is that FS is either unhappy about something in the packets themselves, or possibly with the SDP.

[benlangfeld]

@krakatoa Could you please provide working and non-working PCAPs, as well as high verbosity freeswitch logs of both scenarios?

@bklang liberal-dtmf=true tells FreeSWITCH to accept both 2833 and INFO.

[bklang]

We most definitely are not sending DTMF in SIP INFO. @krakatoa is it possible that the SIP peers you have configured are not set for RFC2833?

[krakatoa]

@benlangfeld the working PCAPs were these (you can download them from that page): https://code.osso.nl/projects/sipp/browser/pcap. And the non-working PCAPs were the ones genererated by SippyCup 0.3.0. Is that helpful ?

[krakatoa]

@bklang Freeswitch is set to use RFC2833.. As far as I know, FS has no current support for RFC4733, however, it worked by running those "2833" PCAPs downloaded from the SIPp page...

[chewi]

I'm having this trouble too with 1.2.17 and sippy_cup develop. I have implemented sending DTMF via SIP INFO instead (using a dtmf_mode option) and this works. I'll submit a pull request soon. As it turns out, I think I'll need to use SIP INFO anyway because it seems like you can't repeatedly send RFC2833 DTMF in response to incoming SIP messages due to the timings in the pcap file being fixed. You would need to break it up into multiple pcap files, if that's even possible.

[chewi]

This obviously still needs addressing but if @krakatoa wants an easy workaround, check out #59.