I mean on Vatsim. Usually if you are not part of any VA you would use N-876DW for example. My doubt is as we are part of AirSource does the callsign apply as any other VA. forxample, SWA, COA, CXA, etc...?
If you want to fly with "Airsource" as your callsign then use "ASO" (I also add Airsource to the remarks as it's not well known). If flying an airlines route then you can use the airlines callsign though using ASO show's your affiliation to Airsource.