Unlocked Apple iPhone 4S Now Available

Apple has begun offering a version of the iPhone 4S that is "unlocked": meaning it can be used with any GSM carrier. It also doesn't require signing a wireless service contract.

Devices bought from carriers are "locked" to that carrier, and can only be used on that carrier's network. Virtually all phones sold in the U.S. are set up this way. With unlocked GSM phones, users can swap SIM cards whenever they want to change which carrier they are connecting to. 

No contract means no carrier subsidy, so the 16GB model is $650, the 32GB one is $750, and the 64GB one $850. These are the same prices paid by wireless carriers' customers who don't qualify for a subsidized upgrade.

Good for Some, Not Good for Others
Apple's website lays out which carriers this version of the iPhone 4S will work with, and which it won't:

The unlocked iPhone works only on supported GSM networks, such as AT&T in the U.S. When you travel internationally, you can also use a micro-SIM card from a local GSM carrier. The unlocked iPhone will not work with CDMA carriers such as Verizon Wireless or Sprint.

The iPhone 4S is offered by both Sprint and Verizon, so it's not clear why users can't use an unlocked unit with these carriers. Units sold by these CDMA carriers even have a SIM card.

T-Mobile USA is notably absent from the list of GSM carriers supported by this model. This is because T-Mobile's 3G/4G services uses frequencies that the iPhone 4S was not designed to work with. Users can make calls and connect over a 2.5G EDGE connection, however.

The unlocked, contract-free version of this smartphone is available now on Apple's website.