Will a T-Mobile iPhone 5 work on AT&T?

I recently switched from AT&T to T-Mobile and want to switch back. I'm still within the 14 days of my Buyer's Remorse Period, the only thing is now i don't have a AT&T phone, will my T-Mobile iPhone 5 work on AT&T?

Yea itl work

If you return the phone through buyer's remorse, it's considered a refund and you must return the phone. I would just cancel the service since there's no cancellation fee and pay the phone off (required before they unlock it)