Help me to stop calling from some bad people.?

I am a Nokia 5310 Music express phone user. I live in Bangladesh, a country of south-asia. I am facing some problem by unknown number calling. They are disturb me so much. Pls give me a name of a software which can be able to stop any call or any number to calling me. If that freeware then really good for me! please help me!!!!!!!!!!!!!!!!!!!