Make your mobile number invalid in Nokia cell phone.If you want to ignore some one but you don't want to switch off your number then you can adopt this method.In Nokia cell phone there is call diverting feature.We will use this feature to make our mobile invalid.

Just Divert your cell to any hello tune number so when he/she called you will get number invalid.

or if you don't know any hello tune number than divert number to Five zero(00000) or Four zero(0000).