Extention to extension calls drop after 30 seconds

[mcclu11]

I've never worked with Avaya phone systems before but a new client called us in to help them with this problem. They have a IP Office 500 and one flat VLAN with the phone system and all phones in the same class C subnet. Calls are not going through a firewall or being otherwise routed, so there shouldn't be any NAT or inspection issues.

A few times per day on a call that is ext to ext, one of the callers will no longer be able to hear the other about 30 seconds into the call. They can hang up, call back, and all is well. Calls to or from outside are ok, and if they call another extension by its DID number those are ok.

All switches on the network are Cisco, I haven't ruled out switch problems but that seems less likely since any other type of call is ok. I tried looking through logs generated by the Monitor application but I'm not sure what I'm looking for to find drops. They say it has always done this very sporadically but in the last week it all of a sudden gotten worse, the only change around that time was adding a handful of new extensions. There's no consistency as far as which phones, time of day, day of week, dept, etc. Any guidance in the right direction is appreciated.

[thiel2]

In Manager, go to each extension, and to the VoIP tab, see if "Allow Direct Media Path" is checked. If it is, uncheck it. See if that fixes the problem. This is not a real, preferred fix, but it will point to the problem residing in the switches/routers.

[mikechesla]

I would add that taking the system through a reboot, if it has not already been tried, should be done.

If that didn't work, I'd have to ask they tried and true troubleshooting question, what, if anything, changed within the network when this problem started occurring. Did they add a switch? New Firewall? Is there a new network analysis tool on the LAN?

It is possible that the module handling the VCM (Voice Compression Module) is failing, though that would be really rare...