Intermittent beeps during a call

Hello, since upgrading to Asterisk 1.6 and dahdi, I have been experiencing intermittent beeps during phone calls. I ran asterisk 1.4 with zaptel for years and never had this issue. The beep sound is not a full DTMF tone, just a short beep at erratic times. The beeps seem to happen most often when connected to callers using other PBX systems. Also, I noticed this most often on long distance calls, not usually with local. I have done a great deal of research into this issue and not found anything yet to resolve the problem. I would be grateful if any one can offer any suggestions on what I might try next.

Background on configuration and what I have tried:

  • set dtmfmode = inband for each extension
  • Set Sipura ATAs to use “DTMF Tx Method=InBandâ€

This sounds similar to my problem, which I have posted the results of my troubleshooting and bug reporting here:

When you make long distance calls, do they go out through your FXS ports, or through the Internet, as a SIP or IAX call?

As I state in my post, you might try placing the call on hold at the Asterisk end, so that music on hold is constantly sending sound. That seems to be what triggers the noise you hear, and why it is erratic during actual phone calls.