Hello,
If you are trying to register the Unit with the private IP to the one with the public ip this is most likely going to create problems. If your modem firewall is not very h.323 friendly you might try setting the extip of the A400 to the external IP address, I’ve seen this solve this problem a few times. Having a look at your gk table might help. If you have any questions feel free to email at
Support@voiphelp.net