[asterisk-users] Handling DTMF for number 4

[Alejandro Cabrera Obed]

Thanks Gareth, when you say that I can choose INBAND for DTMF MODE in
the GSM Gateway, that implies that the DTMF MODE of the Asterisk
extension registered for the GSM Gateway has to be set to INBAND too
or can it remain in RFC2238 ???

Because I have all my Asterisk extensions and IP telephones set up
with DTMFMODE = RFC2238 by now, and I can't understand if you suggest
me I change the DTMFMODE from RFC2238 to INBAND just in the GSM
Gateway or everywhere.

Thanks again.

2010/6/28 Gareth Blades <list-asterisk at skycomuk.com>:
> Alejandro Cabrera Obed wrote:
>> Dear all, I have Asterisk 1.4.23 implemented with an IVR wainting for
>> mobile phone calls coming from a GSM Gateway.
>>
>> All the components are set up in DTMFMODE = RFC2238, and so when the
>> caller from mobile touches the IP phone LAN extension, the call is
>> succesfully established. Everything is OK except for the DTMF for
>> number 4, because if the caller from mobile dial 1004 or 1014
>> extensions -which have the number 4- the calls are errouneosly
>> established with extension 1000.
>>
>> I live in Argentina, but I don't know if the DTMF frequencies are the
>> same than other countries or I have to make a change in somewhere.
>>
>> Can be a problem with the detection of DTMF for number 4 in Asterisk ???
>>
>> Thanks a lot
>>
>> Alejandro
>>
>
> The gsm gateway would be performing the DTMF detection and just sending
> on what it detected as you have the DTMFCODE set as RFC. Maybe if you
> set the DTMF mode to INBAND it may pass the audio straight through and
> allow asterisk to detect it.
> The problem is that mobile calls are heavily compressed so any entered
> digits are converted to tones once the information reaches the network
> operator. As the call is gong back over a mobile connection the DTMF is
> compressed which results in unreliable detection.
>
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-- 
Alejandro Cabrera Obed
aco1967 at gmail.com
www.alejandrocabrera.com.ar