[Freeswitch-users] DTMF strange problems

[Kevin Mathy]

Hi,

I'm facing a "strange" problem with DTMF, on a FS server I'm using (Version
1.5.8b git fe2a4d6 2014-02-14 00:03:11Z 64bit).
For some calls going through FS, when customers send DTMF tones (using
RFC2833), I see those logs :

2014-11-14 15:47:48.516849 [DEBUG] switch_rtp.c:5683 RTP RECV DTMF 1:742
> 2014-11-14 15:47:48.516849 [DEBUG] switch_channel.c:489 RECV DTMF 1:742
> 2014-11-14 15:47:49.056857 [DEBUG] switch_rtp.c:5683 RTP RECV DTMF C:640
> 2014-11-14 15:47:49.056857 [DEBUG] switch_channel.c:489 RECV DTMF C:640
> 2014-11-14 15:47:49.356848 [DEBUG] switch_rtp.c:5683 RTP RECV DTMF 2:661
> 2014-11-14 15:47:49.356848 [DEBUG] switch_channel.c:489 RECV DTMF 2:661
> 2014-11-14 15:47:49.696846 [DEBUG] switch_rtp.c:5683 RTP RECV DTMF 3:665
> 2014-11-14 15:47:49.696846 [DEBUG] switch_channel.c:489 RECV DTMF 3:665
> 2014-11-14 15:47:50.256872 [DEBUG] switch_rtp.c:5683 RTP RECV DTMF 4:745
> 2014-11-14 15:47:50.256872 [DEBUG] switch_channel.c:489 RECV DTMF 4:745
> 2014-11-14 15:47:50.796855 [DEBUG] switch_rtp.c:5683 RTP RECV DTMF 5:741
> 2014-11-14 15:47:50.796855 [DEBUG] switch_channel.c:489 RECV DTMF 5:741
> 2014-11-14 15:47:51.236850 [DEBUG] switch_rtp.c:5683 RTP RECV DTMF 6:664
> 2014-11-14 15:47:51.236850 [DEBUG] switch_channel.c:489 RECV DTMF 6:664
>

Here, the customer tried to send "123456". So, I don't know why this "C"
character has been sent, and I'm sure the customer didn't send this,
because there's no "C" touch on his phone's keypad...
And this "C" results in a double "1" received on the IVR server (hosted on
another server than FS).
(Ex : 123456 => 1C23456 => 1123456)

It doesn't happen everytime, but for around 80% of calls... So it's really
a problem for us...

I looked at PCAPs for concerned calls, and saw that DTMF tones are only
sent with RFC2833, not with SIP INFO nor InBand.
I first thought that digits may be received simultaneously with RFC2833 and
InBand but definitely not.

Do you think what could be the cause of that ? I don't use  "start_dtmf" in
my diaplans, I already saw in other ML topics that this may cause double
digit problems.

Is there a way to ask freeswitch to only handle 0-9*# characters ? Or any
idea, I'll be glad to try anything that can help us !

Thanks for help,

Kevin




*Bien cordialement, Best Regards, **Kevin MATHY* | Ingénieur VoIP

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