Your callsign is your identity.

What use is an F-call? Names are important in day-to-day interaction between people. In amateur radio, you get issued with a callsign that after a little while takes on the role of a name. When you first become an amateur and you meet another amateur, they're likely to introduce themselves, "Hi, I'm Onno VK6FLAB". At first you do a double-take and wonder what the other person is smoking and where you can get some. After a while you realise that this is quite common. If you use your own callsign for a while, you'll get to the point where it attains the status of a name. In day to day interactions with other amateurs, you'll refer to another amateur by either their name or their callsign. You'll recognise them by either as well. It's a little like a surname, but it's different in that this particular name only makes sense among other amateurs. It gets better. After a while, you'll start hearing callsigns after the fact. Someone will say a callsign and you'll not hear it as individual letters, but as a word and you'll be able to reconstruct it. This skill typically happens if you listen to many callsigns, like when you're participating in a contest. Now for a funny part of this. Your callsign can change. If you are mobile, or portable, or operating in a different state, you'll slightly modify your name. When I was using a hand-held in Melbourne a couple of months ago, my callsign went from VK6FLAB to VK6FLAB Portable Victoria. When that happens, your name feels different. Just for completeness, if you're doing this in Morse, the rules are slightly different, but the ACMA website tells you the whole story. Look for ACMA portable operation and you'll find the "Amateur operating procedures" document. It also gets pretty interesting if you operate a club callsign. You'll use that callsign instead of your own. When you do that, a tip for getting it right is to make a big sign in front of your radio with the correct callsign. You'll be amazed how often you refer to it. Your callsign is your identity. I'm Onno VK6FLAB