Will an iPhone 4 from at&t work on simple mobile?

I have an iPhone 4 for at&t but i no longer want at&t want simple mobile will i be able to use this phone on simple mobile?

Yes, but you nay not get 3G/4G data service.

Here's an option: in some cities, T-Mobile is able to provide high-speed (3G/4G) data on AT&T cell phones. They have expanded their coverage to include the frequencies used by AT&T devices, but only in certain cities. You will have to get the iPhone unlocked by AT&T (they should get you a code for free if you tell them your going out of the country). T-Mobile offers no-contract plans with data for as little as $50 per month, which is similar to Straight Talk. (Straight Talk buys their airtime from T-Mobile).

This is a list of cities for T-Mobile's expanded service as of mid-January.

http://www.tmonews.com/2013/01/t-mobiles-network-modernization-what-is-it-where-can-i-get-coverage/