Can you change a nextel phone into an AT&T phone?

My dad has a blackberry that is a little disfunctional, but mostly because its service is provided by Nextel. His calls always drop and the texting is terrible. So, I was wondering, is it possible to change the phone’s format to make it compatible with AT&T or Verizon? Thanks.

Isnt Sprint-Nextel CDMA?

AT&T= GSM

GSM phones have sim cards
CDMA don’t

if your dad’s phone is CDMA theres no way that it can work with AT&T

sorry..