Does anyone know how you can tell if someone has blocked you using their MTN and GLO phones?

What happens if you try to call someone and they have blocked you?

Do you hear a message? What message do you hear? What does it say?

Ese o

Sometimes I get "the MTN number is not available, please try again later"

Sometimes I get "the MTN number is switched off, please try again later"

I have not spoken to this person for a while...I get these messages EVERYtime.

Is it just bad service?

I am wondering if they have blocked me.