Phones are down and unable to get calls.

Started out early this morning unable to make a phone call. Tried calling my son's boost Mobile phone and only thing I was getting was busy signal. I was able to reach out to my other son who does not have boost. He has T-Mobile and it seemed to not even have a problem on his end. Still only able to call certain people who do not have boost. My son's phone when he tries to call out it just rings busy. Hope they get this back up and running soon.