All About MMSI Numbers
By Tim Hasson Updated: June 14, 2006 The acronym MMSI stands for Maritime Mobile Service Identity. Sometimes called a “DSC Number”, an MMSI is a 9-digit code that can be programmed into certain types of radio equipment, such as a marine radio with Digital Selective Calling (DSC). When programmed into marine radio equipment, an MMSI provides a unique, internationally standardized number to identify the vessel. This number also provides a uniform way for authorities to get information about a vessel during a distress incident, and can be used by service providers as a common number for call tracking and billing. In fact, the numbering scheme was carefully designed to allow the worldwide public telephone network to communicate with the equipment on-board automatically. One perfect example of this capability is the SeaSmart service being implemented by SeaTow (see http://www.seasmartvhf.com/ ). Because it makes sending and receiving voice, telex and e-mail messages to ships direct and automatic, it’s convenient to think of an MMSI as being like a telephone number for the boat. While this is certainly true, there are a couple of distinctions worth pointing out. For instance, while it’s common in this day and age to add a second or even third phone line at home, MMSI numbers are designed to be unique to the vessel in question. It’s important when licensing and programming the equipment aboard that the vessel receives only one identity, with the same number programmed into all devices. Like a phone number, devices programmed with an MMSI can be used to “direct dial” another boat, provided similar equipment is aboard the other vessel. VHF DSC is a good example of this use. Increasingly, MMSI’s are also used for contact with shore-based service providers, to place phone calls, send e-mail, or to send/receive telex (teletype) messages. While this kind of direct, one-on-one communication is extremely convenient and “telephone-like”, the MMSI coding scheme actually goes a step further. When used with DSC, the MMSI system also provides for something called Group Calling. It is possible, for example, for an owner to simultaneously call every ship in the line to deliver an important message. It is also possible to hail every Coast Guard vessel or coast station within radio range at the same time. Going even further, in an emergency a DSC-equipped boat can transmit a special distress signal to every similarly equipped station that is listening, on land or sea, including nearby commercial vessels. This alert message, which can be activated with the push of an idiot-proof button, includes the MMSI number of the vessel in distress along with its position (provided the radio is linked to a GPS receiver), and even the nature of the emergency. The safety advantages of this kind of instant, automatic alerting are obvious. Because MMSI numbers are unique, authorities can use them to positively identify a vessel in distress. In the U.S., the FCC and Coast Guard maintain a database of MMSI’s that contains details on each vessel, it’s owner, and homeport. The International Telecommunications Union (ITU) in Geneva, Switzerland maintains a similar, international database which contains the MMSI of every vessel (recreational boats included) which travels internationally. This Maritime mobile Access and Retrieval (MARS) database is accessible by anyone at www.itu.int/cgi-bin/htsh/mars/mars_index.sh. For privacy reasons, access to vessel particulars and emergency contact information is restricted to authorized users only. At this writing the distress-alerting capabilities of VHF DSC are gradually being implemented by the US Coast Guard, but probably won’t be completed universally until 2009. Even still, in the meantime nearby commercial vessels may monitor a VHF distress call and relay to the Coast Guard. DSC on HF (single side band) frequencies is further along, with most US Coast Guard stations now “on line”. The good news is that while the U.S. may be lagging in some respects, this system is in widespread use in Europe and beyond. In fact, DSC and MMSI numbers are critical pieces of an internationally agreed-upon plan called the Global Maritime Distress and Safety System (GMDSS). GMDSS is a major rethinking of the emergency communications capabilities required of commercial shipping vessels. Worldwide implementation of this master plan began in the 1990’s, and is still ongoing (with occasional interesting debate). MMSI numbers are intended to replace the older Selective Calling (SELCAL) numbers used by radio teletype equipment aboard ships. While MMSI’s and other GMDSS enhancements were designed with commercial interests in mind, there is no reason recreational boaters should not take advantage of the safety and convenience these improvements make possible. By international agreement the International Telecommunications Union sets the rules that determine how MMSI’s are assigned and used. In the United States, the Federal Communications Commission (FCC) is responsible for actually assigning MMSI’s to commercial and recreational vessels. An MMSI number can be obtained from the FCC when the radio or satellite terminal equipment is first licensed. If the equipment is already licensed, but no MMSI was issued, it is possible to amend the existing paperwork for a small fee. See the article All About Radio Licenses for details on the license application process. Note that if you have already commissioned an INMARSAT B, C, or M terminal through COMSAT, then an MMSI number has probably been issued to your vessel. As noted above, this same number should be programmed into other equipment aboard, and a new number should not be requested. There is a way for some U.S. users to obtain an MMSI without applying for a license and paying the associated fee. Recreational users who will remain in domestic waters and only carry VHF, EPIRB and Radar are not required to be licensed, but may wish to obtain an MMSI for use with a VHF DSC radio or EPIRB. For these users, the FCC has entered into a cooperative agreement with BOAT/US to assign MMSI numbers and relay registration information to the Coast Guard in the event of a distress call. Registration can be done either on-line at www.boatus.com , or call them at 1-800-563-1536. Likewise, SeaTow is also authorized to assign MMSI numbers to domestic, recreational vessels. Contact them at 800.473.2869 or check http://www.seatow.com/boatingsafety/mmsiinfo.htm for details. Finally, some recommended “Do’s and Don’ts” with respect to MMSI numbers and DSC equipment:
Tim Hasson can be reached at (1) 610.287.0703 or via e-mail to THasson@TechYacht.com . Copyright © 2006 by Tim Hasson |