For many iPhone owners, a big reason to stage a jailbreak is to unlock the device, thus allowing it to work with carriers other than AT&T. (In the U.S., “carriers” means T-Mobile.)

Now, at least two services are promising to unlock any iPhone 3G, 3GS, or 4 without the need to jailbreak. What’s more, they can do it remotely.

Cut Your Sim and GSM Phone Source charge $169.99 and $179.99, respectively, for remote iPhone unlocking. In both cases you supply your phone’s International Mobile Equipment Identity (IMEI) number, then wait a couple days for an e-mail confirming that the process is complete. It’s that simple.

According to Cut Your Sim, this is a “permanent” unlocking solution, requiring no jailbreaking or warranty voiding: “The unlock will work with any iPhone version, and any base band version; no need to worry about updating to the latest version anymore, your phone will be unlocked forever!”

OK, but does it really work? Boy Genius Report put GSM Phone Source to the test and found that it works as advertised: “We have confirmed first-hand that the service does work flawlessly.”

A bigger question might be, is this really necessary? Now that Verizon carries the iPhone, buyers already have an option other than AT&T. What’s more, AT&T is in the process of acquiring T-Mobile, meaning there may not be another U.S. carrier that can support an unlocked iPhone for much longer.

If you’re still keen on unlocking but don’t want to pay such exorbitant rates, there’s another option: the Gevey SIM. This custom SIM-tray/card combo for iPhone 4 also works without jailbreaking and keeps your warranty intact. It sells for $65.

If you’ve had any hands-on experience with any of these solutions, hit the comments and let us know how they worked out. In the meantime, what are your thoughts on iPhone unlocking? Is it worth the time and expense? Or is the need rapidly disappearing?

Originally posted at iPhone Atlas