Some of the current operators, based on Maddog liveries I found.
(Country) Airline: IATA / ICAO / Callsign
(USA) World Atlantic Airlines: WL / WAL / Doral
(USA) Evert Air: 5V / VTS / Everts
(Dominican Republic) Red Air: L5 / REA / Red Dominicana
(Venezuela) Laser Airlines: QL / LER / Laser
(Venezuela) Aeropostal: CW / ALV / Aeropostal
Thanks,
Dan