[asterisk-dev] Strange DTMF received on a incoming call

[Fernando Urzedo]

Hi all,
 
We have a Asterisk 1.4.21.2 box conected to several VoiP trunks and E1
links (through Mediant 1000 gateways), and the calls are sent to SIP
peers. Sometimes, during incoming calls, our users are able to hear some
beeps similar to DTMF digits. See examples below (they are portuguese
conversation, but you can hear the sounds):
 
http://www.katizak.locaweb.com.br/asterisk/beep.mp3 
http://www.katizak.locaweb.com.br/asterisk/beep2.mp3 
http://www.katizak.locaweb.com.br/asterisk/beep3.mp3 
http://www.katizak.locaweb.com.br/asterisk/beep4.mp3 
 
On the other side of the conversation, we are pretty sure they are not
pressing any button in their phones.
 
Do you guys have any guess about where these sounds are coming from? Is
there any configuration that can prevent the SIP peers from receiving
DTMF digits, while they still can send DTMF outside?
 
Thanks for any help you may provide!
 
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