Everytime I recieve a call, I dont hear a thing, I dont hear the voice of p?

Everytime I recieve a call I hear nothing on the other end absolutely nothing no crackling no fuzz and no voice, same applies to when Im making a call I dial the number but nothing, Ive checked all volumes, please help, the phone is a sony ericson Im not sure of the model it has blue top though and silver bottom and one of the older models lplease help