It is prove to be true that starting Sunday, AT&T will let iPhone customers who are off contract with the android 2.3 carrier unlock their iPhones,it means that they can use them on other carriers with similar GSM networks, T-Mobile being the largest of those.

"I personally have certain iPhones that were originally purchased on AT&T but android 3.0 cannot be used on other GSM networks in the U.S. like U.S. Cellular or T-Mobile just because they are still locked to Ma Bell’s system," noted Matthew Panzarino on The Next Web. "This should be a great way for customers with older phones to both increase resale value for those devices and to improve their flexibility when choosing a future carrier."

In one hand,in a statement Friday, AT&T, which was the exclusive carrier in the U.S. of the iPhone from 2007 to February 2011, said:

In the other hand,beginning Sunday, April 8, we are going to offer m009g google android tablet qualifying customers the ability to unlock their AT&T iPhones. The only requirements are that a customer's account must be in better standing, their device could not be associated with a current and active term commitment on an AT&T customer account, and they need to have fulfilled their contract term, upgraded under one of our upgrade policies or paid an early termination fee.

"The ability to unlock an iPhone has been possible for several years, but was until now unofficial and unsupported by Apple and major carriers," wrote Jim Tanous of the Mac Observer. "Today’s announcement tell us that millions of AT&T iPhone customers who have fulfilled their contract agreements are all free to switch carriers based on price now, convenience, and travel, all by simply swapping a SIM card."