A call sign is a unique identifier for a transmitter station used in broadcasting and radio communications. It can be formally assigned by a government agency, informally adopted by individuals or organizations, or even cryptographically encoded to disguise a stations identity. In commercial aviation, the callsign is usually the ICAO Flight number. Call signs are issued by the Federal Communications Commission (FCC) in the United States and are assigned to radio and television stations. The primary purpose of a callbook is to allow amateur radio operators to send a confirmation postcard, called a QSL card, to other operators to confirm contact. In the military, call signs are used as pilot nicknames to quickly identify an individual.
Some additional points to note about call signs include:
- Call signs are only required to be mentioned during station identification announcements in the United States.
- Wireless network routers or mobile devices and computers using Wi-Fi are unlicensed and do not have call signs.
- On some personal radio services, such as CB, it is considered a matter of etiquette to create ones own call sign, which is called a handle.
- Some wireless networking protocols also allow SSIDs or MAC addresses to be set as identifiers, but with no guarantee that this label will remain unique.
- Call signs can be a combination of identifying letters, letters and numbers, or words assigned to an operator, office, activity, etc. .
In summary, a call sign is a unique identifier used in broadcasting and radio communications to identify a transmitter station, individual, or organization.
