Unknown.
One anon posted callsign conventions used by several MIL squads then another anon refuted the conventions from their own knowledge. Apparently conventions are localized and particular to different squadrons. Not a mil anon, just a reserve planefag trying to answer an easy question on the Lakota, kek.
In an computer game, the Non-Player Characters (NPCs) are not real people. They don't have any volition of their own. They are part of the "set" and their purpose is to advance the plot by speaking or acting in predetermined patterns designed by the programmer. They speak canned lines and have no autonomy.
It's the ultimate insult to call someone an NPC. They are programmed and have no mind of their own.