2 things i suggest, first is a PRL update, if you call sprint and tell them to update your PRL update they will go thru the steps with u.
the second is the long way that will most likely suck, but i had a similar problem to this where i did a rom update and my phone constantly dropped calls, i even switched back to the original ROM and still had the same problem
try switching back to the original rom, or even the new leaked sprint rom and see how the service is.
you may need to get a replacement
