Many a times you do not like to accept call from certain people, such as your jealous colleague, ex-boyfriend/ girlfriend or a loan-shark. This can be easily achieved by setting up a voicemail for such calls. Such a feature on Android OS is called Call Filtering. The person who will be blacklisted, will have their calls always go through the voicemail, so he will never be able to call you when you do not want it to!
1. Go to the Contact List
2. Select the Contact you want to blacklist and open it
3. Near the bottom, find and tap the Send to Voicemail option
4. Agree the popup, and Viola! Your contact is blacklisted!
Now whenever the person will try to contact you, he will not be able to reach you and will be redirected to the pre-recorded voicemail.
Remember, this process is completely reversible and you can remove the number from Call Filtering blacklist. This facility can also be used as a temporary call blocker from a particular person.