If you join using my invite, you get a link for 3 invites for you to send out. Once 3 people sign up through your link, you can sign up to register your "callsign!"
I was kinda excited about this title until I found it that it will be a "Free-mium" title.
So between this and the new Mechwarrior in development (Also F2P) I'm pretty sure I'll end up choosing Mechwarrior.