I’m using SIP rather than H323 but I’ve had the best luck putting the device in the DMZ. The host company I’m using recently installed a Kagoor server for NAT traversal. Awesome!
Is not the same, we just did a test passing a SIP call trought three concatinated routers, and the call goes trought like a champ, without any change on the routers.
On the other hand, with H323, it is a miracle to make calls from behind one NAT.
I use only H323 so far, but I am impressed with SIP.
There is solution if you have control (or friends) on both ends of the service.
You could try to close the information loop by forwardind the used portds on the ATA from the WAN I.P. to the internal I.P. behind the router.
Only works with the first ATA behind the router.
If you have control of both ends, you could get it working with around $120.00 dollars for good.
Just get a couple of VPN routers and presto.