AT&T has long clamped down its customer's iPhones to its network. But it's finally easing up: The carrier's  iPhones can now be "unlocked," meaning they can be used on other carriers after a certain period of time.

A spokesman for  AT&T  told the New York Times that the carrier would ease up its policies for customers whose accounts were in good standing and who didn't have a long-term commitment with AT&T. AT&T had no further comment for ABC News.

Those good-standing customers can have their phones unlocked remotely or at an AT&T retail store.

Once their phones are unlocked, owners can use them on other GSM cell and data networks by popping in other SIM cards. In the U.S., the AT&T iPhone is compatible only with T-Mobile SIM cards; Verizon and Sprint use different, CDMA cellular technology.

This capability is of greatest help to those traveling outside the United States. Instead of paying for expensive global service from AT&T, an owner of an unlocked phone  can pop in a SIM card from a local GSM carrier and pay much cheaper local rates.

AT&T iPhone customers could previously  unlock their phones by "jailbreaking" them - through software that circumvented both Apple and AT&T.

Sprint and Verizon have already provided an unlock feature for customers in-contract.