I guess I'm blessed. I've only gotten one call from this number. Illegal, because it was to my cell.

For what it's worth:

I have two smartphones, on two different carriers, from two different makers, using two different operating systems. On both of them, if I make a number like this into a contact, I can immediately block all further calls .... and no app was needed. I usually wait. If there's no second call, there was no reason to block.

I just recently got the second phone, and had difficulty figuring it out. Went online, and the extensive user manual was silent on the subject. Called the provider, and a helpful guy spent more than an hour, stepping me through all kinds of different sequences. Finally, he gave up and said (after checking with supervisor) that the phone could not block numbers. Began to step me through the download and installation of an app. Hit a snag, and I opted to call it quits. Then, I discovered -- on my own -- that making a contact, then saving it to the PHONE (Doesn't work if the contact is saved to the SIM.), brings up a menu option to block the caller. Piece of cake, once I figured out where to look.

So, neither the phone manufacturer documented how to do it, nor the tech support people managed to figure out how to have the phone block callers. But, it didn't take an app (There are free ones.), and if there's ever a second call, it's block city, around here.