If you own an iPhone 4 on AT&T, using the device while traveling internationally means paying sky-high roaming fees, jailbreaking or limiting data use to when you're on a WiFi network, either with a public hotspot or through a service like Xcom Global. Verizon iPhone 4 owners, however, don't have the option of GSM roaming at all, and can only make calls and use cellular data in countries that support CDMA. All that changes with the iPhone 4S, however -- Macworld has confirmed that Sprint will sell its version of the device with the Micro SIM slot unlocked, with Verizon offering free unlocking to customers after the first 60 days of service. iPhone 4S owners will then be able to purchase a Micro SIM overseas, allowing them to access data and make calls at local rates, for a fraction of what it would cost to roam. AT&T iPhone 4S owners won't have this option, however, so if you make frequent trips overseas, this benefit alone may be enough to justify purchasing the phone through Sprint or Verizon, saving some users hundreds or thousands of dollars in international roaming fees. Our SIM does not come out of the device - I believe the same is true of Verizon's iPhone but you would need to confirm that with them. Customers can sign up for one of our international rate plans and use this phone all over the world. When traveling internationally, there is a setting that must be turned on within the device to connect to GSM. The phone will work with a SIM that is provided within the device out of the box. International voice and data charges are on a pay-as-you-go basis and vary based on the country where the customer is using their phone; a list of rates is available at www.sprint.com/international.
Update: Our source article was incorrect, and Sprint has told us that its SIM will not be unlocked, adding that the card will not even be removable.
Update 2: We heard from Sprint a second time, which redacted part of its previous statement. The carrier further explained "the SIM is removable and is not affixed to the device," which as you may notice directly contradicts the statement made earlier today. We've reached out to Apple twice and are awaiting further clarification.