When Apple first released the Verizon CDMA iPhone 4, some guys taking a close look at the phone’s components noticed that the chipset for the CDMA radio also technically supported GSM. While that model was stuck doing CDMA-only, the iPhone 4S fulfills on that dream of a dual-mode radio, enabling users who have a CDMA primary carrier to roam on GSM networks while abroad. That’s the idea, anyway; how will it actually work out?
First off, you’ll obviously need a SIM, which you’ll have to get from the GSM carrier whose network you wish to use. The only sticking point here is that the iPhone 4S takes a micro-SIM card, so if the carrier only offers larger, standard-sized SIMs, you may be stuck trimming one down.
The other main thing to prepare for is to make sure your primary carrier has enabled the phone to support GSM roaming. If you get your new 4S from Sprint, it should be capable of such a thing from the start, but Verizon users will need to make a special request to have their phones unlocked. Before the carrier enables GSM service, you’ll have to have maintained your account in good standing for about two months.
Update: Now Sprint is saying its 4S won’t come with GSM enabled, either.