If you search the net for Iphone 4 mics not working you will find more info and reasons as to why everyone is having the same problem but after having mic problems for months and after searching the net for weeks I found the easy solution! Before you open your phone!
Before you buy a new mic.!
Before you send it in for warranty!
( IF THIS WORKS FOR YOU AND YOU WANT TO THANK ME, DONATE TO MY IPHONE 5 FOUND AT PAYPAL ) zero@zerogrc.com