The 'World Radio' is a CB radio club. The 'World Radio' identifier is registered to a number that is registered to just one person; each number is unique to just one person.
To become a member, one would have to ask a World Radio club administrator on the air >only way< in order to become a member/number. No membership dues are required.
There are many different international/DX CB radio clubs that have different identifiers, such as Sugar Delta, Alfa Tango, India Romeo, and so on. They all have uninque, registered identities for each number within that group.
If you want to join a club, this forum has a radio club 'Whiskey Delta X-ray ('WDX'), and all you have to do is send a private message to the administrator and ask to get a unique number. No cost/charge.
World Radio 11/Robb