

As predicted, Apple has started selling unlocked (GSM) iPhone 4 devices in the U.S. early this morning.

If you don't want a multiyear service contract or if you prefer to use a local carrier when traveling abroad, the unlocked iPhone 4 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.

Pricing starts at $649 for a 16GB model and $749 for 32GB model. Both White and Black models are offered.

The main advantage of buying an unlocked iPhone is for international travel, as the device is not dependent on any particular carrier. The U.S. only has one network (AT&T) which fully supports all the features of an unlocked GSM iPhone. T-Mobile is compatible with voice calls, but the 3G network is not compatible. The higher price of the iPhones reflect no-contract pricing as well as the unlocked status of the device. While the iPhone 4 had been sold unlocked in other countries, this is the first time Apple has offered them in the U.S.