I can't hear the other person's voice or the others can't hear me during the call.

Solution:You need to find the voice memo in the attachment to record a voice and then play it. If you can play the voice, the microphone and the handset are good. It may be the customer signal problem that causes the phone inaudible. If the recording does not respond, the microphone is faulty. If the recording does not play, it indicates that the handset is faulty.