Most iPhones have a SIM lock, which locks the use of the phone to one mobile carrier. This practice is common with subsidized GSM phones (like most iPhones). But SIM-locked iPhones can’t be unlocked by entering a code, the way most GSM phones can be because data on whether the phone is locked or unlocked is maintained on Apple’s servers. However, even though AT&T is the only authorized US iPhone carrier, an unlocked iPhone can be used with other carriers. While you can buy an iPhone unlocked from Apple, they cost twice as much as those that come with contracts to make up for Apple and AT&T’s lost income. If you want to use your iPhone with T-Mobile (the US’s other GSM phone network), you’ll have to unlock it. This is legal, and can be done with readily available, downloadable software.

Is it Legal to Unlock iPhones?

The legality of unlocking an iPhone has been somewhat hazy in the US, but a July 2010 court ruling cleared it up: as the owner of a wireless handset, you have the right to remove restrictions, blocks, or limitations so you can use it with the provider that you want to use. While AT&T still has the right to lock down iPhones, you have the right to unlock them.

What does it mean to jailbreak your iPhone?

Jailbreaking an iPhone is not the same thing as unlocking an iPhone. While unlocking an iPhone lets you switch carriers, jailbreaking an iPhone means you replace the iPhone firmware with a modified version that does not limit your iPhone to software that has the Apple-approved cryptography signature. Though iPhones that have been jailbroken are theoretically susceptible to computer viruses, very few incidents of this type have been reported. Jailbreaking an iPhone lets users install apps that aren’t available in the App Store, and allows such functions as using the camera on iPhones earlier than the iPhone 4 to shoot video.

How should a non-geek go about this?

Unlocking or jailbreaking an iPhone used to be the province of the technologically sophisticated. However, now that the legality issues have been cleared up, there are readily-available, downloadable software applications that allow even the non-technologically inclined person to do this easily and quickly, whether they use a Windows computer or a Mac. The unlocking process takes about five minutes and should not result in any loss of functionality for your iPhone.
Other Advantages of Unlocked iPhones

Besides being able to switch carriers, if you take your unlock iPhone with you to Europe, you can simply switch to a different SIM card with cheap rates for whatever country you’re in. You’ll have a different number, but giving out your new digits to the people you want to be able to reach you is a small price to pay for avoiding hefty international roaming charges.

In conclusion, unlocking and / or jailbreaking your iPhone opens up many possibilities for new uses for your iPhone and allows you to choose which GSM carrier you want to use. It’s legal, and easy, and you don’t have to be a technology wizard to do it.