Zte Majesty Z796c Phone Problems (2)

One phone operates fine except when when ringing a number it is very faint to hear. Upon someone answering, I can barely hear them as it is so faint! I have checked ALL the volume setting and turned to max! Have "reset" the phone to factory defaults and again maxed all settings- still does the same thing? phone #2(also z796c) upon making a call and connecting, the other party says I sound "muffled" they can make out my conversation, but it is not clear and crisp like it was? Both issues showed up out of the blue. There have been no accidents or calmerties with either phone. Whats up???