How can I use a 3G internet connection in my Android App?

I have made an App that can connect to a program that I am running on a server, but it only seems to work with WiFi. When I try to use 3G it doesn't make the connection. Is there something special that I have to turn on or set in order to use 3G?

Solution

The problem was the port I was using. I was using 4444, but it turns out that many networks block that port. Port 1024 seems to work for most.