Help Continuous interference sound during calls

[kooldudej]

Hi Guys.I bought my wildfire a month ago.I have been hearing a constant interference sound during the calls.Initially I thought maybe it's due to bad reception.But it's been happening for the last 3 days.The thing that baffles me is that when I use the earphones or when I turn on speakerphone there's no such interference sound..

Has any of u faced such problem??What should I do in this case??..