Hello everyone. I am currently using an AT&T pay as you go phone service, and have had my current phone for 2 years. I figure its a bout time to get a new phone, and im looking online for phones i like. My question is, what determines what phones are compatable with my service? Is it the GSM bands? The sim card? The provider? The phone? Will any unlocked phone work?

I called my local store and they told me to go in the store and purchase a phone, but im not sure if he was simply trying to make a sale or actually told me the truth. He said some functions such as texting wouldn't work (which ive heard elsewhere as well) And besides, i can buy the exact phones in there for less online. However, my brother was on the same service and bought an unlocked razr and it worked for him, so now i wonder.

Sorry to bombard you with questions - i tried searching for threads but they all seem to not entirely hit the nail. Thanks for any help!

-Rolf