When I make or receive a call I cant hear caller

The problem is either in the speaker contact pads or the speaker itself, not in the micrphone. If you have the tools to disassemble the unit check the contact pads, clean it and lift up the speaker terminals to ensure it makes contact with the pads. If it doesn't work, check the speaker resistance using an ohmmeter. The resistance reading should be 20-30 ohms, otherwise replace speaker.