Verizon spokeswoman Brenda Raney said that Verizon does not plan to lock the iPhone 5 for American carrier use.
If you would like to use your Verizon iPhone 5 with another carrier, you will need a new compatible nano-SIM card for the iPhone 5 and of course an account without another carrier.
GSM bands are more popular in Europe. Verizon on other smartphones offers world roaming to GSM networks for an additional charge. In the past, Sprint locked the iPhone 4S to its CDMA network.
Since the iPhone is unlocked, it will be easier for Verizon owners to take their iPhone 5 with them if they change carriers. However, if you bought an upgraded iPhone 5 with a usage-based plan, you are bounded by a two-year contract and will have to pay an early termination fee.
Be aware however that the Verizon iPhone 5 when connected to the AT&T network will not connect to AT&T's LTE network but its HSPA+ network with slower speeds.
Sprint's iPhone 5 is locked to the Sprint network. It is possible that AT&T iPhone 5 can be unlocked to the Sprint or Verizon CDMA networks. AT&T allows iPhone users who pay full price or have come to the end of their contract to unlock their iPhones.
We will investigate and get back to you.