No Key Needed!
Those of you fortunate to have the Verizon iPhone 5 will be able to use any nano sim on ANY network around the world. This has been tested on multiple networks including T-Mobile as well as AT&T where you can pop in a SIM from the carrier and will be able to make calls and access the 3G mobile networks.
Verizon states that they are aware of this and have NO PLANS on locking the phone. This is a big plus for those who want to be on America’s best mobile network and plan to travel overseas! AT&T iPhones however, are confirmed to be locked (I just tried a few minutes ago).