Souny Ericsson W300i- Problems with disorted sound on imcomin calls

I noticed that my phone has been distorting the sound quality of my incoming calls. Sometimes when I get a call i will hear the person and then they will slowly become distorted then they start to sound which I can only describe as if someone is trying to talk under water underwater or soemthing, like a bubbly noise disrtotion. This will also start to occur when the phone is dialing the person on the other end does not hear anything. I notice this especially happens after my phone had been on silent or is in silent mode.