Maritime Mobile Service Identity (MMSI)

Maritime Mobile Service Identity (MMSI) is a unique nine-digit number assigned to a maritime radio station or a ship, used for identification when communicating over the radio. It is an integral part of the Global Maritime Distress and Safety System (GMDSS), which is an internationally agreed-upon set of safety procedures, types of equipment, and communication protocols used to increase safety and make it easier to rescue distressed ships, boats and aircraft. MMSI numbers are used worldwide by coast stations and ships for digital selective calling (DSC), automatic identification systems (AIS), and certain other purposes. The MMSI number is transmitted digitally, allowing for a quick and accurate transfer of information, and is particularly useful in emergency situations where rapid response is crucial. It is also used for routine communication between ships and between ship and shore. The MMSI number is divided into three parts: a three-digit MID (Maritime Identification Digits) indicating the country of the ship's registration, a unique ship identifier, and a single digit for on-board communication systems.