I have a scenario here which has a single flaw that I am sure is tied to IP address & port binding.

The connected equipment is as follows:

Quadro <-> Internet <-> NAT Router <-> Remote IP Phone #1 & #2.

When only one IP phone connected and registered, full communication both ways with crystal clear service to and from the Quadro.

When two IP phones are connected and registered, only the first has communication both ways. The second has no audio at all. However, the two remote IP phones can call each other and have perfect communication with each other, as well as see accurate BLF of each other as well as the local extensions. Of course, if both are rebooted at the same time, no telling which will get bound properly. If the two are booted opposite (working unplugged & non-working rebooted) the previously non-working begins working, and the original working becomes non-working. This is definitely a source vs. destination port mapping issue. Especially knowing that the two remote IP phones can communicate with each other perfectly because no NAT is taking place locally between them.

I know the problem going out is that the NAT device is mapping the source port 5060 to some random number for both remote extensions but the Quadro is only sending back on 5060, regardless. I thought I could change the SIP port on the extension management page of Quadro to 5061 for remote #2, but that does not seem to make a difference. I know I would also have to change the port on remote IP phone #2 as well.

I am asking for assistance in how to be sure I have the Quadro programmed to communicate with specific extensions on specific ports only. The extension management page does have a SIP port entry field, but these extensions do not register on a sip server so that checkbox Registration on SIP Server is not checked.

Anybody have a sample they can provide me?