Has anyone else ever had this issue?

My iPhone didn't let me make a call because when I tried I couldn't hear the person at the other end
What could be wrong with my Phone?

All brands of phones get like this, from time-to-time. It's just "tired", per se.
What you need to do is use your iPhone until it runs out of battery, and shuts it self off. Then plug it in, and leave it alone until it charges to 100%. Then turn off your phone by holding down the lock button, and slide the "off" option that will show up on the screen. Wait five seconds, and turn it on (hold down the lock button until you see the Apple logo). And there you go--Good as new.
Stay Gold, Ponyboy.