No one can here me

Can they hear you when on speaker phone?

The mic is on the assembly that holds the socket where the charger plugs in. Often a simple cleaning is all that is needed. remove the back>battery>speaker, then you will need to remove the 2 screws that hold down the socket, and lift the clamping lever that connects the home button ribbon. there is a rubber wedge that holds down the corner of the socket at the motherboard. Remove the wedge then carefully lift the lead that connects to the motherboard, while sliding a thin tool under the socket circuit board to assist in releasing the adhesive. there is adhesive in 3 places, 1)under the corner where the cable that goes to the mobo turns up then out, 2)directly under the center of the socket(slide a thin tool under here to release the adhesive here too), and 3)at the opposite side under the ribbon that attaches the mic, slide tool under the ribbon while lifting socket, the mic plugs into a little tube in the chassis, help it slide out as you lift the socket out. now with a toothbrush and rubbing alcohol(and your jewlers loupe) gently clean off all the lint(dry first) on the outside and inside the socket. blow it dry with compressed air. I usually spray these components down with brake kleen then blow it dry. Carefully inspect with magnification, then reinstall, Also check that nothing is obstructing the "tube" that the mic plugs back into(lint, dried soda pop, toilet paper, etc) you should be able to see right through to the grill work. blow it out if necessary. Pocket lint is a major culpret here.