I’ve discovered little inaccuracy with the flight number/callsign combo in specific MSFS flights. As you probably know most of the airliners use callsign similiar to the flight number. Basically flight number is shorter by one letter:
Example Air France
AFR118 callsign
AF118 flight
but also some flights are different - You can have for example AF1259 flight number and AFR13QL callsign. And also I have to add that callsign in real life with AFR is not AFR or Alpha, Foxtrot, Romeo, but ATC address Air France as “Airfrans”
Example Qantas
QFA191 callsign
QF191 flight
Simbrief wrongly marks it as QFA191 flight and the callsign is the same. This time it is correctly addressed in game (ATC), because this flight dont use the numbers and two letters combo after numbers.
Example British airways
BAW4TH callsign
BA400 flight number
ATC in real world uses SPEEDBIRD 4 Tango, Hotel
When creating flightplan you can start with the flight number, but Simbrief then wrongly uses the airline ICAO code to put it in front of the flight number - as I shown it is always wrong, because from QFA it is QF, from AFR it is AF from BAW it is BA etc.
So you correcly write BAW (airline icao code) and 400 flight number, but instead of BA400 you get flight number in dashboard BAW400= wrong.
Then in next step you can modify your callsign in the simbrief menu, you can rewrite the default BAW400 to the correct BAW4TH - but you cant write in the callsign Speedbird 4TH, because it is set to 7 characters only. Even if you write it here in format BAW4TH and you load your flightplan into the FMC/MCDU in your airliner (thanks to simbrief integration) you are going to overwrite the callsign (even if you set your callsign in the menu, when you choose where and in which aircraft you want to spawn). Game ATC wont call you BAW4TH, Neither Speedbird 4 Tango, Hotel (even if you set it in game menu), but will cal you BAW400 (or British airways 400).
But the sibmrief integration in various aircrafts influences the callsign if you load the flightplan from simbrief (when you load it in game from fmc/mcdu). Ingame ATC starts to address you as BAW400, not as BAW4 Tango, Hotel. Like I said if the flight number = callsign with one letter difference, e.g. AF118 and AFR118 ATC address you the right way, but when you load the simbrief plan you cant set the AFR13QL in game, and if you set this callsign in the game menu before you start flight. The callsign is going to be overwritten as soon as you load flightplan from simbrief. Only way how to avoid this is put in flightplan manually waypoint by waypoint, airway by airway and set callsign in the flight menu before you start the flight.
From flight planning section Simbrief takes ICAO code for airline (AFR) and flight number (1259) and in dashboard it recreates from these two values Flight number AFR1259 which is wrong. The correct flight number is AF1259