International travelers, think twice before you buy an iPhone 4S for its "worldphone" capabilities from a U.S. carrier. You'll be able to use that iPhone overseas, but only at obscene prices with the carriers chosen for you. If you want a real worldphone -- that is, one where you can use any GSM carrier's MicroSIM in the countries you visit -- you need to wait until November to get the $649 unlocked iPhone 4S directly from Apple or get the $549 unlocked iPhone 4 from Apple today.
It should be illegal for carriers to lock you into their partners when not in their coverage regions, but the United States allows it and the carriers do it. In many other countries, this practice is illegal, so cellphones and smartphones can be used with any carrier, not just the one you bought it through.
In practice, what all this means is that anyone who does serious travel overseas needs to get the unlocked Apple-only version of the iPhone 4 or 4S, and then sign up for a contract for domestic service with AT&T. That's right, only with AT&T. The unlocked iPhones do not support CDMA networks, which are what Sprint and Verizon Wireless use. So the price for international usage freedom is being stuck with AT&T, whose network is mediocre in many parts of the United States. (You could also use T-Mobile USA, but your iPhone's data usage on that network is limited to slow 2.5G connections.)
I don't get why Apple made that "unlocked means GSM only" decision. Maybe the market is too small to have added Sprint and Verizon variants, but Apple could have used its market power for good and forbade carriers from locking out overseas carriers as the price for carrying an iPhone. After all, that's what it did for the iPad, and the same carriers have done quite well in that environment. Of course, the Verizon version doesn't support (or claim to) GSM networks, so the unlocked status of the AT&T iPad may not mean all that much after all.
It's true that some non-iPhone worldphones are similarly locked -- this evil practice is driven by the carriers, not Apple -- so you need to be careful no matter what worldphone you buy. But I know many people who thought that Apple's idea of a worldphone would be a better one than the carriers'. They were wrong.
This article, "Beware the iPhone 4S's 'worldphone' trap," was originally published at InfoWorld.com. Read more of Galen Gruman's Mobile Edge blog and follow the latest developments in mobile technology at InfoWorld.com. Follow Galen's mobile musings on Twitter at MobileGalen. For the latest business technology news, follow InfoWorld.com on Twitter.