Yesterday I was using my iphone 4 to make and receive calls, and working properly. Today I try to make a call and the receiver part of my phone is not working, the other person can hear me, but I can not hear who I am speaking to, and yes the in-call volume is all the way up. The only way to actually have a convo with someone is to put them on speaker. Does anyone know how to fix this? PLEASE HELP?!?!?!