Can't hear the caller. He can hear me, though

It sounds as though there's something wrong with the microphone.

Have you tried using an external headset?

Your explanation of the problem is not too clear.
If you receive a call and you cannot hear your caller but your caller can hear you, your speaker is bad and will need to be replaced buy phone technician.
If it is that you can hear your caller but they cannot hear you, then your mouth piece is bad and need to be replaced.
Because of the Miniature nature of the Cellphone circuit there is user serviceable part

Did you drop your phone? It seems that your phone's caller speaker is damaged thats why you can't hear the caller. If this is the problem then the only solution is to replace the speaker. Hardware is not covered under warranty, but you should check with the warranty provider. Otherwise, take it to any mobile repair shop and ask them to change the speaker.

Looks like there is a connection issue internally or speaker might not be sitting in its place . PLease visit the authorized service centre .

1. Just dial *67 before the phone number on your cell phone. This code is the universal command to deactivate caller ID.
   
   For example, placing a blocked call would look like*67 555 555 5555 (without the spaces). On the receiving end, caller ID will usually display "private number" because it has been blocked.
   
   Though you won't hear or see a confirmation of a successful caller ID block, it will work.

Change the Microphone of your headset through some authorised service personnel.

*****

We just had the same problem with our AT&T 2462 hand sets. They simultaneously stopped transmitting, and though we could hear the caller, no one could hear us on the other end of the line. We unplugged the base from the power source, took the batteries out of the hand sets, waited 20 seconds, then plugged everything back in and they worked just fine. Hope this helps.

you ear piece may need to be replaced you should take the phone to a repair shop and have them replaced the ear piece or look at the old one for you.

These phones have been known to have some mic problems (usually buzzing) when the mic's connector wire becomes loose from the mainboard. This happens most likely during shipment of the phone.

Though it definitely sounds as though the mic is not working, just to be more convinced it is the mic, try doing a voice recording to see if that fails as well.

Unfortunately the only 2 ways of fixing it are taking the chance yourself to take the phone all the way apart without breaking it to get at the mainboard connection and secure the mic wire, if that's truly all it was, or to send the phone back for replacement.