Accepted caller blocked

[LadyTay1]

This past week I received a call from my brother. He was using his wife's cell phone. He told me he tried to call using his cell but got a message that his number was blocked so he had to use his wifes phone to call me. His number is not on my block list and I did not block his number. After some research I found: I set up to block callers with their caller ID blocked. My brother said he does not block his caller ID.  Why was his number blocked?