Hello. Recently I have found problem which was in callcenter application. Agents randomly had heard a beep sound like calling members where pushing some number to send a dtmf done. This was annoying, because this was in a middle of conversation. This tone had appearing randomly not on every incoming call to callcenter. It was high volume of 0.5-1 sec long. I couldn't track the source of this sound, as in the resulting recorded file of the conversation there where no suspicious sounds, nor a beep from callers, nor the beep from or to agents. So I was lost. Several days ago I remembered about using start_dtmf application on incoming calls from phone provider because the do not use rfc standard for dtmf. More strange thing was that this strange beep sound didn't appear on regular incoming call to some extension. It was only when external callers from phone provider were calling into callcenter number. So I used stop_dtmf just before sending incoming call to callcenter application. With this command those strange beeps disappeared. Then I've changed start_dtmf to spandsp_start_dtmf and didn't use spandsp_stop_dtmf. Beeps does not appear too. So there seems to be a problem with core handling of in-band dtmf with start_dtmf aplication when call is routed into callcenter, and the callcenter bridged the call to the agent. Should I rise an issue to the jira, or this is an internal known issue of core dtmf handling and will not be resolved? Mimiko desu.