Originally Posted by
the810
FR24 does show true callsign in addition to the flight number. They will use ICAO code (e.g. BAW) instead of spelling the airline callsign out (e.g. Speedbird) but the number they show is the real callsign, not just public flight number. For example, this is flight EY154 with the call sign Etihad One Quebec November:

I shall stand corrected here and apologise😥 I should have realised from my recent investigation of EK406 punctuality - the flight has UAE1CR callsign most of the times...