Dolphins2012:
My mid is a 2/C. His phone (at&t) worked beautifully the first two years. This year, he does not receive calls or texts in his room. Unlike "other" schools, he cannot walk & talk, so on his way to class we cannot call him. He has to go outside to talk to us, which is the case for some of the rooms in Bancroft. The texts come in when he is away from his room.
I don't think provider makes a difference in this situation......just the location of the room. He can talk from a buddy's room just fine.
I typically text and email him. Mids get a bunch of email daily, so he is always checking that.