iPhone or AT&T... Can You Hear Me Now???

Lately my iPhone has been glitching out... I have the iPhone 4, or should I say it has me!  I am stuck in a contract with AT&T and my phone has started to not register calls which are placed to me.  I get the messages after I have missed them, when I return a call missed, the person on the other end of the line can not hear my voice, at times if my voice does get through to them, it is usually only for a moment and then we continue to exchange "Can you hear me nows"... fun huh!

I am resetting to factory specs at this time... I will let you know how that works out.