why can i hear people when i call them but they cant hear me?

[AC Question]

From today, when I call anyone they can hear me but I can't hear them? Can you help?

 

[B. Diddy]

Welcome to Android Central! Which phone, and which carrier? Can they hear you if you turn on speakerphone, or use a wired/wireless headset? If so, then either the primary phone mic is faulty, or it's blocked by some debris--check the mic opening.