Wireless zero configuration and VOIP

I have a wireless conection and I have a VOIP phone. Unless I turn off WZC
my calls will only last between 1 and 2 minutes. However if I do turn off WZC
then I can make calls a lot longer. However, after about 10 minutes my
wireless connection appears to be active but getting to the internet no
longer works. I then start WZC and it works great. When I need to make a
phone I must stop it. Please help with advice as to how I can get through
this without constantly starting and stopping the WZC.

Howard