The unlocked iPhone 4S sales officially began in November 2011 through Apple their website and in Apple Stores. An unlocked iPhone 4S is sold at a high price because of the lack of a contract subsidy, but the main benefit is that the phone may be used on any suitable GSM network through the purchase of a microsim card. In the USA, this implies an unlocked iPhone 4S works with T-Mobile, AT&T, plus some pay-go plans. Moreover, anybody in possessing an unlocked iPhone 4S can use the product in another country by simply picking up a local sim card, preventing costly roaming fees. Pricing for that contract-free unlocked iPhone 4S came in at $649/$749/$849 for that 16/32/64 GB models respectively. The unlocked gadget is suitable only with supported GSM networks, and Apple offers top tips on which customers might benefit most by buying an unlocked AT&T iPhone 4S. “The unlocked iPhone includes all the features of iPhone but without a contract commitment. You can activate and use it on the supported GSM wireless network of your choice, such as AT&T in the United States.* The unlocked iPhone 4 or iPhone 4S will not work with CDMA-based carriers such as Verizon Wireless or Sprint. If you don’t want a multiyear service contract or if you prefer to use a local carrier when traveling abroad, the unlocked iPhone is the best choice. It arrives without a micro-SIM card, so you’ll need an active micro-SIM card from any supported GSM carrier worldwide. To start using it, simply insert the micro-SIM card into the slot on your iPhone and turn it on by pressing and holding the On/Off button for a few seconds. Then follow the onscreen instructions to set up your iPhone.” The company's retail stores, however, were selling off-contract AT&T iPhone soon after launch, with customers discovering that those devices were also coming through unlocked.