As of today Apple started selling unlocked iPhones. The unlocked phones are SIM Free and can work on any GSM network only. This phone will not work on CDMA networks such as Sprint and Verizon.
Interestingly Sprint started SIM locking their iPhone 4S starting today. And of course the iPhone 4S sold at Sprint until yesterday were unlocked. And let us see how long Sprint will keep them (un)locked.
Here is what Apple is saying about it.
“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.”
Head over to Apple online store if you are interested in getting one.