In Chris's final year in Atlanta why didn't Chris's parents call him?

I don't think Chris had a phone, he kind of lived like a monk.

Chris did not have a phone.

"During that final year in Atlanta, Chris had lived off campus in a monkish room

furnished with little more than a thin mattress on the floor, milk crates, and a table. He kept it as orderly and spotless as a military barracks. And he didn't have a phone, so Walt and Billie had no way of calling him."