Display works great, calls to and from main office are good, but no audio on remote IPT's. I am on my way to remote site now. Any ideas?

I think these are the same phones that have been in service for the last 2 years

A change to the RTP ports on the network?

Turn Diffserv off and see if that helps. Depending on how many hops it takes for the IP phone to connect back to the phone system, one or more hops may not be configured for Diffserv causing a drop in Voice. I know it sounds like a stretch but I've had this happen.

Has the ISP change settings and your LIPU card is now going through NAT

Voyager and I talked about this on the phone. Seems IP calls internally work fine. It is when the IP phone call thru the PRI or get a call thru the PRI that their is no audio. I used to have a fix to this on a document but can't seem to find it for the life of me.

I'd question the same as petersog : has NAT been introduced?

or for that matter... anything different about the IP/Network setup at all?

Have you checked the timing source on the pri ? i have found before that if the timing source isnt set or locked up then rtp wont work.

Update - Thanks for all the responses. The customer took the IP phone home, plugged it in and it worked just fine. This tells me that the problem is in the router at the model home office. The "IT Guy" is going to look at it tomorrow and let me know what he finds.

Resolution .....

IT guy went in and replaced the firewall with one that supports VOIP traffic and the problem is solved.

Thanks for all the responses

Gotta love that!

Thanks for the follow up.