The unlocked iPhone 4GS will only work on supported GSM networks, like AT&T in the U.S. But it will not work with any CDMA carriers, including Verizon Wireless or Sprint.
Customers who buy an unlocked iPhone 4S will be able to use the handset internationally on GSM networks. They must obtain a micro-SIM card from a local GSM carrier to put in the handset.
When it was announced on Tuesday, the iPhone 4S was unveiled as a "world phone," meaning it is compatible with both CDMA and GSM networks. But customers who want to operate the handset on a CDMA network, like Verizon, the largest carrier in the U.S., will need to buy Apple's latest smartphone with a new two-year contract.
"The unlocked iPhone includes all the features of iPhone but without a contract commitment," Apple's description reads. "You can activate and use it on the supported GSM wireless network of your choice, such as AT&T in the United States."
The contract-free iPhone 4S is available in all three standard capacities, and is priced at $649 for 16GB, $749 for 32GB and $849 for 64GB. It will be available in both black and white.
When the iPhone 4S is delivered in November, it will arrive without a micro-SIM card. By inserting a card and turning on the phone, users will be able to activate the device by following the onscreen instructions without tethering to a Mac or PC, a new feature made possible by the PC-free setup in iOS 5.
Apple has warned that a credit check may be required for customers who purchase the unlocked GSM iPhone 4S in November. In addition, customers must be at least 18 years of age to buy.
The unlocked iPhone 4S will arrive only a few months after Apple began selling the GSM iPhone 4 unlocked in June. The contract-free iPhone 4 also carried a starting price of $649.