Block unknown numbers from iphone4?

Some one keeps on stalking me and keeps calling me. Ive contacted my server company but they said they can't do it ( I'm on optus) theyve suggested I should change my number for $55 dollars but I don't Want to, it's so expensive! I don't Want to jailbreak my iPhone either. I know who they... show more Some one keeps on stalking me and keeps calling me. Ive contacted my server

company but they said they can't do it ( I'm on optus) theyve suggested I should change my number for $55 dollars but I don't
Want to, it's so expensive! I don't
Want to jailbreak my iPhone either. I know who they are but I've told them to stop but they still keep on calling me! I recognize her voice, she acts like she has an Indian accent but I know it's her but she won't admit it! Is there anyway to block these calls and texts from unknown numbers without jailbreaking
My phone? I've already told server company, but they don't provide
This service
3 answers 3