VOIP Talker LAN ok, WAN not

I have VOIP Talker working well on my LAN, when I connect to my listen server on WAN I cant hear any audio. Port 7777 is ok and I can join the session and see every one, however for some magical reason VOIP does not work over WAN. I have forwarded every port to my server and cannot understand why this is happening. Any help would be greatly appreciated.