iPod touch magicJack app error on certain networks

Hey there everybody. I got an app called magicJack, its great, you can make REAL phone calls with a ipod touch using wifi. Using my internet network at home is fine, but using the one at my local school does not work. magicJack gives me "Connection error 3" when I try to make a call. The network has a username and password which I both have and entered correctly. Safari does work with the network. Thanks guys, Regez.