With the latest incarnation of Ultrasn0w, the iPhone Dev Team has given us the first tool allowing for full carrier unlocking of the iPhone 4. (Ultrasn0w 1.0-1 works for iPhone4 baseband 01.59 and 3G/3GS basebands 04.26.08, 05.11.07, 05.12.01 and 05.13.04.) Note that you will need to jailbreak your iPhone to allow support for unapproved apps first, using something like the recently unveiled browser-based jailbreakme. From there, Wired says the whole process, “from virgin iPhone 4 to jailbroken, carrier-independent iPhone takes seconds.”
And yes, it’s legal.
Like jailbreaking, carrier unlocking will void your warranty, and Apple does not very much like the practice. But the Library of Congress’ recent ruling explicitly legalizing phone jailbreaking also gives the goahead to carrier unlocking: Yahoo’s Christopher Null writes that “now anyone can jailbreak or otherwise unlock any cell phone without fear of legal penalties, whether you want to install unsupported applications or switch to another cellular carrier. Cell phone companies are of course still free to make it difficult for you to do this — and your warranty will probably still be voided if you do — but at least you won’t be fined or imprisoned if you jailbreak a handset.”
But the biggest roadblock to carrier-switching isn’t the cell phone companies, but the iPhone 4 itself: Like past iPhones, it’s a GSM phone, meaning it won’t run on CDMA networks like Verizon’s or Sprint’s; this is a distinction which exists at the hardware level. This limits most iPhone 4 carrier unlockers in the US to T-Mobile, which doesn’t even support the iPhone’s 3G network. Now if that rumored dual GSM/CDMA chip comes to the next generation of iPhone, things will get interesting … provided Apple doesn’t ditch AT&T of its own accord first.
Related: Our primer on GSM vs. CDMA.
