Some times when I fly in live I see people with Callsign such as “captain jack” as seen below. I don’t see how it is possible to have a Callsign in lower case letters and with spaces because if you write your Callsign you have to do it in capital letters with no spaces and a max length of 8 letters. I am just asking for the question, how do they do it?
Back in the days you were able to input pretty much any callsign you liked. Then there was a policy change for obvious reasons (people invented pretty stupid and offending callsigns) which made it impossible to create callsigns with lower case letters and have them read out.
If you had a callsign such as this before the policy change, you could still keep it afterwards unless it was offending. So, he probably had that callsign before the change and is keeping it.
Oh I found him while checking how displayname, callsign, and plane name are grouped together on training server. You are right, Captain jack is his callsign.