Weird Ip Problem

My ip used to work when I hosted games ex: esf & cs. But recently we have integrated our phone line kinda like vonage or packet eight which are digital phone services via internet. I have cable and my ip is still the same as it was before, but when i want to host a game, my friends tell me that it keeps retrying to connect. using the connect (your ip) in the console but dosnt work anymore. I give them the exact ip but it wont connect i check un check lan game and everything. Whats goin on????