I am re visiting an issue which I had a few year back but never got resolved but was not a priority at the time.

I have set up a LAN to LAN VPN with Vigor 2830 as server dial in (main office) and Vigor 2860 (branch office) as the client dial out. The VPN is up and working as I can access resources on the main office network from the branch office such as the CCTV system.

In the main office is a Samsung Office Serv 7030 with an Office Serv SMT-i5220 phone at the branch office. The phone logs in, shows when other extensions are busy and can dial fine but when on a call there is no audio in either direction.

This may be a firewall issue but i'm not sure what ports and protocols are allowed / blocked over the VPN.

I am also not sure what if any monitoring I can do to find the issue.

Any help much appreciated.

Thanks

There shouldn't be any firewall blocking through the VPN but if the PBX is issuing some broadcast maybe they're not getting through, but perhaps there is some connectivity to an external/public address on the PBX and it's not actually going through the PBX. Maybe a STUN server is needed... I'd ask support.

so SIP (port 5060) is going across your VPN but not your RTP traffic.

First I'd find out what RTP ports your PBX is using.

Then Id check the phone to make sure it's pointing to the IP of the PBX.

No audio is typically a firewall issue and your RTP traffic isnt getting through.

could it be that your phone is registering via WAN and the PBX is sending audio via WAN but your firewall is blocking.

I imagine your phone/PBX arent communicating over VPN.

Start a wireshark trace on the phone/PBX, make a call and then filter by VOIP and see what's going where.