Is it a Verizon Wireless phone? If it isn't then you won't be able to activate it with VZW.
Verizon Wireless doesn't use SIM cards, so swapping out phones isn't as easy as swapping out the SIM card. If it is a Verizon Wireless phone you have then all you need to do to get it activated is dial *228 and select option 3. Follow the prompts and enter in the required information to get the phone activated and programmed.
Hope that helps.