We have a Asterisk 220.127.116.11 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 bellow (they are portuguese conversation, but you can hear the sounds).
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!