Traditionally carriers like Sprint and Verizon, that use CDMA have been the more draconian as far as rules go on their network (e.g. locking down phones, only allowing ringtones through their service, disabling bluetooth OBEX on phones, etc). That's why people tend to see GSM carriers in a better light (also because GSM phones are compatible with carriers around the world).
YEah I tried to take an old Sprint phone in to Verizon to get it activated when my wife lost her phone. They said technically it would work, but they were not "allowed" to do it.
