AT&T go phone SIM card in iPhone 4?

I'm going to another state by myself to visit family and I need to be able to call my mom to check in. I have a AT&T iphone 4 that is locked but my mom said she could call and have them unlock it. Would I be able to use a AT&T go phone SIM card to put in my phone? And how do they work? It is very confusing.

I'm told that it would not work but I have seen SIM cards put in places and it did take out the battery under it is a slot for SIM see if its compatible and fits in…