Remote phones drop connection 20 seconds into checking voicemail

Hi, I have a Trixbox 2.2 server running FreePBX 2.3. All working fine except that connections to phones linked in remotely via ADSL are dropped by the server 20 seconds into checking voicemail. Regular calls, conferences etc. work fine with no dropouts so it does not look like a NAT problem.

Anyone else having this and any suggested things to try before I start posting debug traces? I’ve raised this over at the Trixbox forums too.

Thanks

I have exactly the same issue… i don’t even know where to start with this so if you have any luck with a solution, please post here (plz, plz…)
thanks