I have a three character tail number. We'll call it N9AZ. When I request flight following I say "RV Niner Alpha Zulu", "Experimental Niner Alpha Zulu", or "November Niner Alpha Zulu". I've noticed that when I start it with "November" it goes right on through, but when I use the other equally accurate phrases I'm asked to confirm that "Niner Alpha Zulu" is the full identifier. I'm training myself to always say "November" but I'm curious about the experiences of other short numbered folks.