I can only hear a caller when using the speaker phone otherwise it is like my phone is on mute although they can hear me. Any possible solutions appreciated, not ready to replace just yet.

Hello there,

My dear friend, the problem is simply that the earphone of the bad/ damaged that is why you cannot hear anything on the phone. As long as your caller can hear you but you cannot hear them, then it is confirmed, because, the speaker is on a different side of where the earphone of the phone is.

The solution is just for you to have the earphone of the phone replaced.

But before replacing the earphone of the phone, you can use a bluetooth hands-free temporarily or an external earpiece that you can connect to the phone and be using on the phone temporarily before replacing the earphone of the phone.

Using a bluetooth hands-free or external earpiece is quite cheap and is of easy access.

Hope this was helpful to you.
Goodluck
Elect_Comp