During a call I can hear the person on the other end, but they can not hear me.

Hahahaha i think i know what's going on!! that is if kay's not right good one kay, kay you are soo hotttttt holla!... anyway if you use bluetooth headset or something it goes default to the headset, if it's in range, some headsets auto accept, and it's easy to accidently tell your phone to alwys connect when in range. also it's a good idea to see if your phone hasn't gotten stuck in bluetoth mode.

another option, backup your phone delete your outbox, inbox sent and drafts and delete your call history , i'm trying to tell you to free up as much phone memory as you can that includes pictures vids music(these phones are prone to act bad when your memory is even close to full.
turn off your phone take out batery and sim and wait 3 mins, then reboot phone.

one more option if that doesn't work then to a master reset. if that doesn't work, then like sexy kay said, you need a new mic.

i'm trying to give hopefull answers. ....

Possibly the mic is broken, try recording yourself on ur fone with voice recorder, if it wont record like that then its ur mic x