D-linkVoIp DVG-1200M battle.net Problem.

I am having problems with my D-link VoIp DVG-1200M.
The problem

Gaming issue with VoIp DVG 1200M
I play a game called "Starcraft" and I have called blizzard.com hotline to ask if there was any way to resolve my problem and they said that it was the VoIP that I use that causes the problems.

The problem I have is, whenever I create a starcraft game, users are unable to join the game due to "high latency"
I can only play a game with 'one' other person or everyone drops.
I have tried port forwarding and had no luck.
http://portforward.com/english/routers/port_forwarding/Dlink/DI-604/Starcraft.htm

Well, the game works fine when I plug my cable modem directly into my router instead of my VoIp box. But when ever I have my Cable modem pluged into the VoIp and having VoIp into the router, the problems occur.


*Note at first I thought it was because of the router that caused the problems, but I was wrong. It was the VoIP box that caused the starcraft gaming problems. I first used D-Link Dl-604 router and now I'm using a brand new Linksys WRT54GS. I am for certain that it is the VoIp box that is causing my problems. Is there anyways I can fix my problem?

I have spent MONTHS trying to figure out what the problem is and now that I am for certain it is the VoIp DVG 1200M and not the routers, Please help me resolve this issue!