[Asterisk-Users] DTFM tones almost completly muted.

[Ian Hailey]

steve at daviesfam.org wrote:

>On Fri, 22 Apr 2005, Peter Bowyer wrote:
>
>  
>
>>On 22/04/05, Ian Hailey <asterisk at dinplug.com> wrote:
>>    
>>
>>>Hello everyone,
>>>
>>>I am trying to receive DTMF commands on asterisk from PSTN calls
>>>terminated at my asterisk box. I have tried to terminate the PSTN calls
>>>with both SIP and IAX using sigate.co.uk and voipuser as the PSTN
>>>terminator. When I listen to tones sent from the PSTN side (e.g.
>>>continuous DTMF tone of about 3 seconds) on the asterisk server (stored
>>>in the voice mail) the tone is more or less completely muted, just the
>>>initial tone start can be heard. I am using the G711 codec. Does anyone
>>>have any idea if these tones are on purpose muted by the service
>>>providers or any other reason why it does not work?
>>>      
>>>
>
>
>Most likely the DTMF tones have been detected at the point where the call 
>was converted PSTN->SIP/IAX, and forwarded instead as an indication (ie 
>via SIP INFO or RFC2833 or whatever.  So you won't hear them in a 
>recording of the audio stream.  The remaining blip is just the little bit 
>at the start before the gateway recognised the tone.
>
>You should receive the indication in your SIP or IAX connection and 
>Asterisk should see it (but its not audio any more).
>
>Regards,
>Steve
>
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>
Hi Steve,

Good point, it makes sense that this is what is happening and most 
likely at the PSTN termination point. The question is where has the 
signalling gone as I seem not to receive it at my asterisk server. Do 
you think that this is a configuration problem at the PSTN terminators 
site or do they do this on purpose so they can charge extra for the 
information etc?

Thanks.

Ian Hailey.