I've been working on getting i2004 phones set up at remote offices. The customer just had a VPN set up using Cisco pix 506 units. We using the VPN for the phones. I've gotten the phones registered okay. The ip phone can call the main office t7316 phones just fine. When we call another IP phone at another remote site, we hear ringback but once the other side answers, there is no audio.

It's a little struggle to get cooperation from the data guy and I am sure this is a network issue. I don't see why he would need to open ports since it's over a VPN. Isn't all traffic encapsulated in the VPN?

Can anyone offer any advice or have you had a similar issue and a solution?

I ran into a similar problem with a pix firewall and the outcome was that the data guy had to make modifications to the default pix "fix up" protocols in the firewall. Also make sure you have the remote gateway in your IP sets programmed correctly.

i tested with an I2004 at the BCM location and called a remote i2004 and the audio was fine. So my problem is definitely from one remote i2004 to another remote i2004.