Hi i have a nokia. Hi i have a nokia n95 and when ever i make or receive a call it goes all

Question

Hi i have a nokia n95 and when ever i make or receive a call it goes all crackly and sometimes the person at the other end cant hear me. if i press or jiggle the bit when the microphone is, it sometimes works? Is this a case of replacing the microphone, and if it is, is it difficult or expensive to do?