Decision is decision, due to a reason or the other, you might make up your mind that you do not want a specific number to successfully reach you on your line anymore. Of course it is possible; I mean, nothing is impossible. Simply follow the few steps I’d be highlighting below, and NOTE! I have tried and confirmed it to work on just an Android device alone.
The first thing to do is to either save the number on your Phone contact, or move the number from Sim contact to Phone.
Go to your Phone contact, locate the number, and click on it.
After clicking on the number, press the option key on your phone and mark the checkbox beside: Block incoming calls
That’s just all, the number will not be able to call you anymore. I’m not sure if the number won’t be able to send you text messages ‘cos: the option was “Block incoming Calls . Whichever ways, just have it in mind that whenever you get to change your phone, or insert your sim card into a different phone, even if Android, if the number coincidentally tries calling you, it will be successful. Incase you later have a change of mind, you can simply undo the blocking by locating the number again and “unmark” the check box beside Block incoming calls this time. You might want to move the number to your sim contact too.