Maritime glossary
Call Sign
A unique alphanumeric code assigned to a vessel’s radio station, used for voice and data calls at sea.
Definition
A call sign is the identifier for a ship’s radio station, assigned by the flag administration when the vessel is registered. It is broadcast in the AIS static data alongside the MMSI and IMO number, and it is used to address the vessel over VHF and HF radio. Like the MMSI, the call sign is tied to the current flag and changes on reflag. Maritime call signs follow the ITU prefix table, so the first characters reveal the country of registry.
Worked example
A Marshall Islands tanker might carry a call sign beginning with V7, the ITU prefix block allocated to the Marshall Islands.
How Vessel Hunter uses Call Sign
The call sign sits in every Vessel Hunter record next to the MMSI and IMO number, so a partial radio log or port nomination can be matched back to the right hull.
Related terms
- MMSIMaritime Mobile Service Identity
The nine-digit identifier broadcast by a vessel’s AIS and used to route VHF radio calls.
- AISAutomatic Identification System
The VHF radio system every commercial vessel uses to broadcast its position, course, and identity.
- Flag State
The country under whose laws a ship is registered, which sets the regulatory standard for the vessel.
The bigger picture
Call Sign is one piece of the commercial maritime picture Vessel Hunter pulls together for shipyards, suppliers, service providers, and port agents. Every vessel record bundles AIS, ownership, inspections, dry-dock history, casualty record, classification status, and a verified contact for the operator decision-maker behind the ship, so the team that reaches out first wins the work.
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