How to fix the "That verification method isn't working right now. Please try another method" screen.

I was trying to get my phone number off my old account that my brother was using, but every time I try to add my phone number its keep saying "That verification method isn't working right now. Please try another method", and the tab says "Blocked", and at first I thought my account was block [for Some reason], but I could still sign in, Then i tryed to refresh a few times. but that also didnt work, and the thing is I can put the phone number, back on the other account, but not on the other one i'm trying to get it on.