One of the biggest complaints users had about the original iPhone was that it was locked down to AT&T in the states and lacked a diverse amount of carriers worldwide. Since the release of the iPhone 3G, Apple has expanded the supporting list of carriers to over 70, but that still isn’t stopping users from unlocking their iPhones, and if you’re in Finland, you can too.

Users may unlock their iPhones for various reasons such as to increase the resale value of their device by being able to sell it to anyone regardless of which carrier they’re on or to switch to another carrier that offers a better cellular plan. While unofficial methods exist such as unlocks supplied by the iPhone DevTeam and those developed by hacker extraordinaire, George Hotz, Sonera of Finland is offering a special deal to it’s wireless customers.

With the release of the iPhones 3GS earlier this year, users were excited to upgrade their devices but had to pay off their remaining contracts to purchase the newly upgraded iPhone. If a user payed off their contract, their old iPhone was essentially contractless and as a token of goodwill, Sonera offered to unlock their iPhone. Keep in mind, this is the last generation iPhone 3G, but even though it’s last year’s model, it’s value goes up significantly due to it being unlocked. What is even more interesting is that the unlock is officially sanctioned according to Olly Farshi The Apple Blog:

And now I’ve discovered that Sonera is also happy to lend a helping hand in unlocking your old iPhone 3G. When the 3G was released last year, Sonera customers had to sign up for a two-year contract. When upgrading to the iPhone 3GS, those same customers are given the option to pay off the remainder of their original 3G contract. Paying off the contract, and thus completing the two years prematurely, entitles the customer to have their iPhone 3G unlocked.

The helpful assistant at the Sonera store made a note of my IMEI number and then passed it onto his boss — after that there’s a special piece of software that only his boss is authorized to use. This mystical application submits the IMEI to Apple, which in turn authorizes the device for unlocking.