I'm working at a site that is running remotely from the main PBX its working off Officeserve 7030 and the problem is that at this remote site out going calls immediately drop after being answered but only on land lines. They work fine if they are receiving incoming calls and calls to cellphones in and out also work fine it's just specifically landlines that the call goes through and rings at the other end but as soon as it's answered nothing is heard and the call drops. I checked the port forwarding and their should be no IP conflicts its on a separate V-Lan. Any ideas on what it could be or what to look for.