User blog comment:Kvant 1/Battle of the Aces: Razgriz, Galm, Garuda, and Mobius./@comment-98.224.225.6-20111018203847/@comment-1824272-20111018204201

No, his actual callsign IS Mobius 1. SkyEye said it himself in Mission 1: "Your callsign is Mobius 1." But you are right, Ribbon is not his callsign, it's just a nickname people gave to those who earned a ribbon insignia.