Many marine communication devices, including marine radios equipped with Digital Selective Calling (DSC) and Automatic Identification Systems (AIS) equipment rely upon a 9-digit Maritime Mobile Service Identity (MMSI) number to identify itself and more importantly the user of the device.
Most new marine radios have a special Distress Alerting Capability that will, upon the touch of a button, transmit a distress message which can include its identity (MMSI) and location - only if the radio has been programmed with a MMSI and is connected to a electronic positioning system (e.g. GPS, LORAN). The Coast Guard recommends DSC-equipped VHF radios for all mariners because of these capabilities.
The U.S. Coast Guard and the National GMDSS Task Force are concerned that many users of these devices are not obtaining, registering and/or properly entering their assigned MMSI into these devices. Lack of an MMSI will make some of these devices inoperable, such as AIS, or incapable of operating advanced features or distress alerting capabilities of the device. Leaving the MMSI unprogrammed, entering a false identity or not updating a previously-programmed device with your own identity may delay a rescue and under certain situations is unlawful.
MMSI use and registration greatly assists the U.S. Coast Guard in responding to an alert since it contains a description of the vessel and telephone numbers used to contact the vessel's owner or point of contact in an emergency. MMSI numbers are issued by the FCC if the vessel requires a Station License, otherwise they can be obtained from Boat U.S. (www.boatus.com/mmsi), Sea Tow (www.seatow.com/boating_safety/mmsi), and Shine Micro (www.shinemicro.com) often at no charge. Those having MMSIs should keep registration information current, including phone numbers, address, name and type of boat.updated: 4/1/2008