Did you buy your new iPhone 5 without a contract? We'll, if you bought it from Apple, AT&T or Verizon, you can have it unlocked pretty easily.
The reason why some like to have an unlocked iPhone is because the phone can be used worldwide and with different cellular providers. It's especially beneficial for people that travel constantly. The phone carrier you have in United States may not be available in another country, so having an unlocked phone that can be used on other phone carriers is essential.
If you bought your non-contract iPhone 5 from AT&T at full price, you probably noticed it didn't come unlocked out of the package. But you can easily unlock it by simply restoring the iPhone via iTunes. After restoring the phone, the user is greeted with the following message:
From there, you can trim your micro-SIM card into a nano-SIM card for the iPhone 5—or just use your nano-SIM of choice.
Usually, phone companies are reluctant to unlock their phones because of the possibility of having the customer change carriers. So why has AT&T allowed their iPhone 5's to be so easily unlocked? It might have to do with Verizon offering unlocked iPhone 5s for everyone right out of the box—permanently—whether you paid full price or the subsidized cost.
Well, why would Verizon want to even offer unlocked phones? Simply put—they have to. Verizon is being forced to unlock their phones by the FCC for using the 700MHz spectrum that is being used by the LTE iPhone 5.
With Sprint, there is no easy way to unlock the iPhone 5. Customers in good standing for at least three months can ask to have them unlocked for international use only. Speak to the proper representative and they should unlock the phone for you.
The last resort would be to wait for the iOS 6 jailbreak. It should happen soon enough.