Quote Originally Posted by sr98user View Post
Russell,

Maybe I was not clear when I listed my NAT entries. My ATA uses 16384-16482 for both incoming and outgoing calls. It just increases by 4 after each call to get the next port number and cycles through the range again. I think this port number is communicated through the SIP packets. The adapter probably finds out the translated port number using STUN server if its used. I don't know a lot about how its communicated to the media gateway. The translated port number on the public side could be different depending on the router.
Yes, there are a lot of missing pieces of the puzzle which folks like me don't understand - e.g. what kind of negotiation of port number takes place. And, now that Tim has mentioned that "old" routers (which don't do any of the new fangled stuff work fine), how exactly do those routers know to let audio traffic from the media gateway in (e.g. is the ip address of the media gateway - different from the SIP server - part of the information that is exchanged in the negotiation)?

I have a really old router which worked fine with many VOIP companies and also with VOIPo until a couple of weeks ago. At that time I port forwarded. I'm tempted to undo port forwarding and restart all pieces after reading Tim's comment that old routers should work fine. Unfortunately, the wife volunteers three evenings this week and the phone needs to be "perfect" for any incoming calls - so it'll be next weekend before any such experiment.

My router does not appear to let me specify what type of traffic to forward - so presumably it's forwarding both TCP and UDP (and not just UDP).