What does it mean to lock a number?

[jmorovan]

My friend dialed a number on my phone and I don't want that person to call back anymore. The only option I get when I click on the number is to save it or to lock the number. What does it mean when I lock the number?

[yahyah30]

locking anything like a message or a number means it cant be accidently deleted someone would have to unlock it then delete it to block a number you have to call