JACKSBORO, Tennessee — On opposite sides of the county jail, a mother and her son chat about school, girls, birthday gifts — and their future together. They aren’t allowed to see each other face-to-face, so the inmate and the fifth-grader connect by video. “Hi, Mommy,” 10-year-old Robby says to Krystle Sweat, clutching a phone in the visiting room as he looks at his mother on a screen, sitting in her cell. Robby hasn’t hugged her since Christmas 2015, just before Sweat wound up back behind bars.