N80 callers not heard

You may have the privacy mute turned on, the one which allows you to say rude and insulting asides to someone next to you and the other party on your phone can't hear that.
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My loudspeaker stayed on, but here is the solution for not being able to hear the caller:
I chatted with Motorola, as I had this problem. Here is their response:
While on a call, press the center button(press the side only to the right) this will give you option to adjust the call volume of the phone......
So, the real answer is close. While on a call, you have to hold down the right outside edge, or ring, of the center key. While holding it down, turn up the volume button on the right side of your phone. It worked for me. Hope this helps!

This is a problem that has to do with the speaker of the phone(not your loudspeaker but the small one). It is probably broken and as a result, there is no way you can hear your callers.
One way to confirm this is for you to put your call on loudspeaker when it comes in and you have picked it, if you can hear your caller then you are sure that the smaller speaker is faulty.
Also, you can try to use a very compatible earpiece or headset and see if you can hear your callers.
If this happens to be the case there is only one way you can get this to work and that is by sending it to a qualified repairer as the phone requires serious expertise so as not to damage it an further.
hope this solution helped solve your problem? please comment for more information and thank you for using the fixya.com website

try to change a new ear piece to make a good out of voice from your caller....

change the speaker

Your handset thinks that you have headphones connected.
Make sure there is nothing stuck in the headset connector port, and make sure it is clean.
If thats not the problem, then it may be cured via a software upgrade or it may need a hardware repair.
Either way your gonna have to take it to a shop to be done, unless youve got the required equipment to hand.

ya you could try just by pressing the $ button ....to start the loudspeaker ,.....

regarding the pin broke , u shd replace it .. clean it with ...soft ( dry ) cloth ..

what happen to my nokia n95 when i call i cant hear ringing, and i just hear it when they answer already my call?

dear replace the speaker of ur phone in k300 the speaker and ringer are the same if u not have new speaker then short both point of the speaker to gather will be ok.