my iphone 4 mic is working in recording but its not working in call

Welcome to Apple Support Communities!

Verify that you do not have a BlueTooth device connected to the phone (the BlueTooth icon in the top bar should be greyed out).

Try inserting and removing a headphone plug several times.

When you are on a call tap the audio selector (the upper right icon on the Phone screen). If you see the number pad "flip" the display with the "Hide Keypad" button. See what device the phone "thinks" it is using.

If none of these resolve the problem reset the phone (you will not lose any data) by holding the HOME and SLEEP buttons at the same time until an Apple logo appears (takes about 10 seconds of holding).

If the problem still remains Restore iOS using iTunes on your computer.

Were you able to fix your phone? I am having the same problem. However, when I use voice memos the audio recorded is very faint. I have replaced the mic and am still having the same problem. I believe the problem is not the microphone but rather a different piece of hardware that is quieting the audio to nearly nothing. People can here me blow into the phone on a call, but that is all.

Daniel