Verizon Wireless and Sprint allow users to unlock their iPhone even when it is within the contract period. But AT&T till now has refused to unlock out-of-contract iPhones. Hence, AT&T subscribers had to get their iPhones unlocked by third-party entities. However, finally now, AT&T is allowing its out-of-contract iPhone subscribers to unlock their devices.

SIM-free iPhone is an important factor for frequent flyers. While travelling overseas, users had to pay for expensive mobile services from AT&T. As a cheap alternative, buying SIM card from a local GSM mobile service provider is best option.

AT&T has not revealed why they reconsidered unlocking iPhones after refusing to do so till now. Recently, Apple CEO Tim Cook had asked AT&T to unlock a subscriber's out-of-contract AT&T iPhone 3GS. Subsequently, users started urging AT&T to unlock their out-of-contract iPhone's too. But AT&T ignored their appeals, perhaps because it feared losing its valuable customers to Verizon and Sprint. Both Sprint and Verizon allows users to unlock their iPhone for international use, even though the device may have been used for a short time period. The only criterion to unlock in-contract iPhone at the two firms is that user's account must be in good standing.

As of now, AT&T's unlock policy is only for out-of-contract users and less favorable for international usage if it is within the contract window. It is hoped that AT&T might also change its policy for worldwide travelers.

"Beginning Sunday, April 8, we will offer qualifying customers the ability to unlock their AT&T iPhones. The only requirements are that a customer's account must be in good standing, their device cannot 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," said AT&T in a statement.

(reported by Johnny Wills, edited by Surojit Chatterjee)