Earlier today I banned a certain individual on the India Broadband Forum for unacceptable behavior.
He turned out to be one of the annoying chaps. In fact he did not restrict to creating fake accounts and posting profanities on the forum… He went ahead and started calling me at around midnight.
Since I am using stock Android, my Nexus 5 does not have an internal feature for call blocking. I could have installed some third party app but there is a simple way out. Found it via @nsm2285.
This works if you are not subscribed to Voicemail service on your operator.
Add the numbers you want to block to your address book under an easy to remember new random contact. Than redirect the calls from that contact to Voicemail.
Since your Voicemail service is not functional and the forwarding number does not exist, the calls pretty much gets nulled.
Simple and effective way to block certain numbers from calling you. If you want to add more, just add them to the same contact.
Feel free to comment below if there are any issues with this method. Or there are better ways out there!