My son has not received a call from UNC, but he has received calls like that from 5 or 6 other schools. I don’t think it means much. The schools ran the gamut from safties to matches to total reaches, including public and private universities. I think it’s something some schools do sometimes.
He’s also received emails from current students, who I assume are working in Admissions office. Some out of state schools have had students from our state email my son to tell him how they dealt with the switch from NC to Boston or Chicago or wherever. My son liked those personal messages, but I don’t think the AOs have targeted him for any special admissions considerations.