Crosstalk ? party line on sip trunk?

I have an Astrisknow system with Freepbx. DID/DOD SIP trunk. All extensions are on local net/layer2.

I am getting the odd report of “crosstalk”. Agents report this as hearing an incoming call ringing in their ear while they are on a call.

I have a sonicwall (I know) with SIP and RTP ports forwarded to the PBX.

Any suggestions would be greatly appreciated, or just point me in the right direction for troubleshooting this issue. We had a PRI before and never saw issues like this. However, the PBX with the PRI was recreated from scratch when going to SIP trunks.

Phones are Asstra 6731i’s.

There has been a similar report from another user who uses If you are using, you should file a report with support.