Dialtone keeps playing during call

Hi all,
I’m having a weird issue with my Asterisk installation that I couldn’t find any help with on the 'net yet. Perhaps one of you here can shed some light on my issue, or at least point me in a new direction for tracing the bug.
For one of my GS users/devices, with each and every call he makes (doesn’t matter which direction, both external and internal), the dial tone keeps playing in the background. Both participants in the call can hear it.
The console log -vvvvvv looks identical to any other extension, no hints to any background() or similar stream mixing command.
dialplan show also returns identical results for his extension and any random other extension.
I’ve rebooted the phone already, done a firmware update on it, his device is almost definitely ok.

Our site is running v11.8.1 bundled with FreePBX, approx. 150 users on a mix of GrandStream GPX2140 and Digium D40 devices on SIP.

Which channel technology driver? If VoIP, what sort of phone?

Another thing to try is tcpdump. Before you make a call, as root, enter…

tcpdump -i any -w outfilename.pcap

Open in wireshark, use Telephony/VOIP Calls, and you can listen to the RTP from either side of the call to see when it’s originating. Check the flow, and look at the packets for that single call.

[quote=“david55”]Which channel technology driver? If VoIP, what sort of phone?[/quote]The problematic end user is on SIP, g722 codec, Grandstream GXP2160 regular cheap desk phone.

Dialtone is generated by the phone and should cease before Asterisk is even aware of the call.

I may have used the wrong word then (English is not my native language) - I was talking about the beeps that are normally only played while the other party’s phone is ringing, which I’m pretty sure is generated by Asterisk.
It’s these 1sec tone/3sec pause tones that continue to play in the background during the call.

That’s ringback tone and where it is generated depends on the dialplan.

As long as you don’t answer the call before initiating the outbound call, it will be generated by the phone. (There are complications if you call Progress, as it could be early media.)

I’ve taken tcpdumps of all four legs of the call now, and noticed that the background beeps were present in both paths, from the callee to the asterisk, and from the asterisk to the caller. This made it clear that they are generated by the phone itself.
I have now flashed a new firmware on the affected phone, and the weird ringback noise seems to be gone.

Thanks for your help!