What is a RAZR2? Droid RAZR / MAXX? Was there a second flip RAZR after the 1st? Droid MAXX? If you are wanting to use a smartphone in place of a basic phone, then you must change plans to an advanced device plan. If you want to replace a basic with another basic, you can do that as long as it is a clear ESN and is Verizon-compatible.
There were RAZR phones on multiple networks. You have to make sure it's a Verizon compatible RAZR. The ones from Tmoble, or AT&T won't work on Verizon. But if you find one built for the Verizon network they should activate it for you.