Apple has started selling unlocked iPhones in their Apple retail stores. What they mean by unlocked is that they can be purchased without getting a contract with AT&T or Verizon. These unlocked iPhones have been available in other countries for awhile now but they’re not available in the US. The Unlocked iPhones are only the GSM models which require a SIM card. This is good for people who don’t want to be restricted to using AT&T who can use any other carrier who supports GSM. This is also good for people who travel internationally, who can easily swap out the SIM card and use their iPhone 4 on a local carrier and not have to outrageous fees to AT&T. If you’re planning to buy an iPhone and use it on T-mobile, you should know that you won’t be able to use the iPhone T-Mobile’s 3G network.
Speculation is brewing that Apple decided to do this because they’re trying to sell as many iPhone 4 models to make room for a new production line of iPhones that is being called by rumor sites iPhone 5. Read all our iPhone 5 rumors here.