not totally true what spike5000 says. but your ability to activate a phone from another carrier on the VZW network depends on a couple of things.
1. the phones type needs to be CDMA
2. you will have to program it yourself, using info from a phone that is currently activated WITH verizon.
I know a person at another forum that has a Razr from Telus and has it active on Verizon, but they did all the proper programming themselves.
And ive seen other people who have a phone from one carrier, flashed to a second carrier, and running on a third carriers network. Again, all that programming was done by the individual and not by the carrier(s)