[Freeswitch-users] intermittent DTMF duplicate digit detection

Thu Sep 8 22:41:39 MSD 2016

I see that you are using a CopperCom IP card.  What exactly is that (I
cannot find any info, have they gone out of business?)  If it is a T1/E1
card, then you will only be able to use INBAND signalling, unless the card
generates RFC2833 for you.  Have you checked the settings/parameters for
this card?  Does this happen to you if you use a plain SIP provider or from
a SIP phone?

Guillermo

On Thu, Sep 8, 2016 at 10:33 AM, Mirko Brankovic <mirkobrankovic at gmail.com>
wrote:

> start_dtmf  you need to start only if you receive in-band (tone) dtmf.
> If you are receiving rfc2833 then it should be rtp event packed picked up
> by FS by default, so
> RTP RECV DTMF 9:1280 means you got RTP EVENT with duration 1280 sent by
> source like that. This you should be able to see if you tcpdump/ngrep on
> that server.
>
> So I suggest disable start_dtmf and do the tcpdump to see if you will
> receive RTP EVENT when dtmf is ignored.
>
> mirko
>
>
>
> On Thu, Sep 8, 2016 at 3:01 PM, Jeff Crews <jeff at eoni.com> wrote:
>
>> Thank you very much.
>>
>>
>>
>> Those descriptions help understand the relationship much better.
>>
>>
>>
>> So I am only using PCMU and PCMA codecs.
>>
>>
>>
>> My only active SIP profile was already on: dtmf-type=rfc2833 with
>> liberal-dtmf not specified…however I added liberal-dtmf=false anyway just
>> to be sure.
>>
>>
>>
>> Then I made sure anything with start_dtmf or start_spandsp were disabled
>> and made a test call to the IVR.
>>
>>
>>
>> I made three test calls and dialed a signal digit of 9 on the IVR menu
>> and each of the three times…it routed perfectly with log entries like this:
>>
>> 2016-09-08 05:09:33.086731 [DEBUG] switch_ivr_menu.c:424 digits 9
>>
>>
>>
>> Then on my fourth call…I dialed the same numbers and the IVR menu kept
>> playing as it was as if no digits were detected at all.  This is the
>> symptom that led me to a person suggesting I place the “start_dtmf” at the
>> beginning of my inbound routes for my user needing the IVR menu.  After
>> placing 10 calls using the same Verizon Droid Turbo mobile phone, on 10
>> calls, 50% of the calls resulting in the IVR not hearing the DTMF and the
>> IVR recording played on.  I tried dialing several times the 9 digit…and no
>> improvement.
>>
>>
>>
>> In running a: tail freeswitch.log | grep –i dtmf
>>
>> I see nothing with the text dtmf in the log when the DTMF is not detected.
>>
>>
>>
>> Then I tried 10 more and all failed to recognize DTMF dialed while the
>> IVR menu was played.
>>
>>
>>
>> Then I added back start_dtmf on the inbound route for this customer.
>>
>>
>>
>> Then I could consistently get the DTMF to be recognized.
>>
>>
>>
>> I started two SSH sessions tailing the freeswitch.log to look for
>> “digits” in one and case-insensitive “dtmf” in the other.
>>
>>
>>
>> I did 20 test calls from the same mobile phone, no speakerphone, dialing
>> 9 each time.
>>
>> In 20 calls only 1 call got double digits received by the
>> switch_ivr_menu.c.
>>
>> When I did see double digits…I got an entry like this:
>>
>> 2016-09-08 05:49:15.846749 [DEBUG] switch_rtp.c:6874 RTP RECV DTMF 9:1280
>>
>>
>>
>> I placed 30 more test calls
>>
>> 8 had double digit 9, 2 had triple digit 9 and the other 10 were good
>> with only single digit received.
>>
>> Again when duplicate digits occurred I got entries in the log from
>> switch_rtp.c
>>
>>
>>
>> Last week when I noticed duplicate digits were received I added IVR menu
>> options for each menu entry so that if 2=sales I added 2, 22 and 222 to all
>> go to sales to keep calls flowing until I can figure this out.
>>
>>
>>
>> Does anyone know exactly what does “RTP RECV DTMF” indicates?
>>
>>
>>
>> Would packet capture in wireshark show something?
>>
>>
>>
>> Jeff
>>
>>
>>
>>
>>
>> *From:* freeswitch-users-bounces at lists.freeswitch.org [mailto:
>> freeswitch-users-bounces at lists.freeswitch.org] *On Behalf Of *Guillermo
>> Ruiz Camauer
>> *Sent:* Wednesday, September 07, 2016 10:43
>> *To:* FreeSWITCH Users Help
>> *Subject:* Re: [Freeswitch-users] intermittent DTMF duplicate digit
>> detection
>>
>>
>>
>> Jeff,
>>
>>
>>
>> Just a couple of pointers.  Inband DTMF detection is handled by spandsp
>> and only really works if you are using PCMU or PCMA codecs (it does NOT
>> work if you use codecs that compress like G.729, etc.)  Spandsp analyses
>> the tone frequencies received and tries to determine which DTMF was sent.
>>
>> RFC2833 works by sending a special packet in the RTP stream, no analysis
>> needed.  You should only specify ONE DTMF method for a channel if you don't
>> want to have duplication problems.
>>
>> You should set <param name="dtmf-type" value="rfc2833"/> and <param
>> name="liberal-dtmf" value="false"/> in the sip profile so that it only
>> accepts RFC2833.
>>
>>
>>
>> Regards,
>>
>>
>>
>> Guillermo
>>
>>
>>
>> _________________________________________________________________________
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>>
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>
>
>
> --
> Regards,
> Mirko
>
> _________________________________________________________________________
> Professional FreeSWITCH Consulting Services:
> consulting at freeswitch.org
> http://www.freeswitchsolutions.com
>
> Official FreeSWITCH Sites
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> http://confluence.freeswitch.org
> http://www.cluecon.com
>
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-- 
Guillermo Ruiz Camauer
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