My son has a Verizon, and I can't stand getting a call from him. Sounds like Daffy Duck on crack on those calls. I can't answer that, other than to say do a web search, and good luck! Nextel and Verizon don't use compatible tech. If you aren't under a contract, use the grace period each one gives to find out which phone you are happiest with.
It could be the phone you are using that is causing the problems, rather than the carrier.