The rumors were true: Apple is now selling unlocked iPhone 4 models at its online store starting at $649 for the 16 gigabyte version, and $749 for the 32GB variant.

The unlocked phones appear to be a less restrictive version of Apple’s current model for AT&T’s GSM network. That means they’ll work on any GSM network worldwide, but they won’t work with T-Mobile’s 3G network in the US since it uses different frequencies than AT&T (it will however work over T-Mobile’s slower EDGE network).

And of course, the phones won’t work on Sprint and Verizon’s network at all since they use the competing CDMA network standard.

Given the price and relatively obscure advantage of the unlocked iPhones, they’re clearly not aimed at general consumers. Instead, they’re more suited for business users who want to use their iPhone while traveling internationally, or power users who don’t want to be locked into an AT&T contract.

Apple notes on its website that the unlocked iPhones don’t come with a micro-SIM card, and that you’ll have to provide your own activated micro-SIM to get the phone up and running.

Apple has never offered an unlocked iPhone in the US, most likely due to the exclusivity arrangement it had with AT&T for years. But with the iPhone now on Verizon, and with a T-Mobile and Sprint launch rumored to be happening within the year, it makes sense that Apple would offer a completely unlocked model. The company already sells unlocked iPhones in international markets where consumers are used to having freedom of carrier choice.

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