Speaker problem in Nokia C2-02 mobile?

[suriyasant]

Hi, i have a nokia c2-02 which i was using due to it's battery backup and i have to make a lot of call with my friends office colleagues in fact im a calling freak on mobiles. But from a while my handset is started giving problem that the speaker where we listen is not giving proper sound of the caller. But when we listen from the back where the camera is placed voice sounds crystal clear. What is the problem and what should i do to get the rid off from it.