My apologies, this phone is GSM but it is on T-mobile instead of AT&T.
sue, what determines the network a Straight Talk phone uses is the model of the phone itself. Straight Talk predetermines, beforehand, what network each model phone they sell will use before you purchase it. It will use that same network for the life of the phone while it is being used on Straight Talk and no matter where you travel in the U.S.
This particular phone is GSM running on AT&T and will use AT&T no matter where it is purchased or where one goes in the U.S. It will work in your ZIP code.
However, if you prefer a Straight Talk phone that uses Verizon, then do not choose this one.
The Straight Talk ZTE Valet and Savvy both use Verizon but are priced a bit higher.