[Freeswitch-users] DTMF Problems! In-band detection patchy, rfc2833 not working!

Kristian Kielhofner kris at kriskinc.com
Tue May 24 23:08:43 MSD 2011


Michael,

  I'm not really sure what you mean by this...

  The DTMF method used between an endpoint and a SIP carrier is
largely determined by the SIP carrier, not the carrier or device on
the far end.

  On the PSTN DTMF is always inband.  If configured for out of band
DTMF it's up to the various media gateways in use by VoIP providers to
detect the inband DTMF, squelch it from the G711 input audio, and
create out of band events.

  Of course if you're configured for inband and using G711 it will be
inband all the way through.

P.S. - Cell phones either use AMR or EVRC these days and I would guess
they're using out of band DTMF too.  I've seen some documentation
claiming support for inband DTMF on either but that seems strange to
me...

On Mon, May 23, 2011 at 10:24 AM, Michael Collins <msc at freeswitch.org> wrote:
> Sidharth,
> A mobile phone will always send DTMFs in-band, so you need to be ready for
> that scenario. I recommend you add this to your dialplan for inbound calls:
> http://wiki.freeswitch.org/wiki/Misc._Dialplan_Tools_start_dtmf
> Test various scenarios and make sure they work - call from Skype, from
> mobile phone, from a land line, etc. Let us know what happens.
> -MC
> On Sat, May 21, 2011 at 1:11 AM, Sidharth Kshatriya
> <sid.kshatriya at gmail.com> wrote:
>>
>> Dear Friends,
>>
>> I'm using a voip carrier Voicenetwork.ca (recommended by someone on this
>> list). While I'm generally happy with their service there seems to be one
>> fatal problem: My IVR does not recognize DTMF!
>>
>> I have set <param name="dtmf-type" value="rfc2833"/> in both
>> sip_profile/internal.xml and sip_profile/external.xml
>>
>> The symptom of the problem is that making a call via skype will always
>> make the IVR recognize the DTMF while using something like a mobile phone
>> almost always won't!
>>
>> I've tried in-band detection too. I'm making international calls into my
>> IVR and the reliability of the in-band detection is not so good, possibly
>> because of the quality of the call.
>>
>> Can someone please help me?
>>
>> Thanks,
>>
>> Sidharth
>>
>> --
>> Sidharth Kshatriya
>> www.sidk.info
>>
>>
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>
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-- 
Kristian Kielhofner



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