Why am I only able to talk via hands-free?

[iMore Question]

can only talk on hands free or the person on the other can't hear me.
I have restarted the phone numerous times, still no luck

 

[phreddyl]

There might be something wrong with the mic on the handset. Do you have AppleCare? Can also try a can of air. Sometimes it gets clogged with dust and lint