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Federal Communications Commission
445 12
St., S.W.
Washington, D.C. 20554
News Media Information 202 / 418-0500
TTY: 1-888-835-5322
DA 16-513
Released:  May 9, 2016
Enforcement Advisory No. 2016-04
Enforcement Bureau Reminds Mariners of Marine Radio Rules Protecting Public Safety
What Are Maritime Mobile Service Identity (MMSI) Numbers and How Are They Used?
Many vessel owners are required to have ship radios on their vessels.  Many of these radios are capable of 
sending automated messages that the U.S. Coast Guard and other search and rescue authorities rely on to 
locate vessels in distress.  Therefore, it is critical for owners of vessels with certain ship radios
to comply 
with Federal Communications Commission (FCC) rules requiring accurate information in these 
automated messages.  These automated messages include the Maritime Mobile Service Identity (MMSI) 
number, a unique nine-digit number assigned to ships with certain kinds of radio equipment.  Search and 
rescue authorities, including the Coast Guard, use the MMSI to learn background information about a 
vessel in distress (e.g., owner's name, intended route, and other radio equipment on board) and to 
determine whether the alert is false.  An accurate MMSI database helps to protect lives and property at 
sea by reducing the time needed to locate vessels in distress.  However, the use of an unauthorized MMSI 
can seriously compromise search and rescue efforts, including misdirecting search and rescue forces and 
alerting the wrong emergency contacts.  The Coast Guard estimates that approximately 10,000 vessels’ 
MMSIs are inaccurate on any given day.  
Specifically, we refer to ship radios that use Digital Selective Calling (DSC) or Automatic Identification System 
(AIS) equipment.  DSC is an internationally approved system for automatically contacting vessels on MF, HF, and 
VHF frequencies.  It allows mariners to send an automatically formatted distress alert instantly to the Coast Guard or 
other rescue authority anywhere in the world.  DSC also allows mariners to initiate or receive distress, urgency, 
safety and routine radiotelephone calls to or from any similarly equipped vessel or shore station, without requiring 
either party to be near a radio loudspeaker.  It allows users to “direct dial” and “ring” other maritime radio stations.  
AIS is a maritime navigation safety communications system that provides vessel information, including the vessel's 
identity, type, position, course, speed, navigational status and other safety-related information, automatically to 
appropriately equipped shore stations, other ships, and aircraft.   
2Who Needs an MMSI, and How Must an MMSI Be Obtained?  
Vessel owners must obtain an MMSI from the appropriate source prior to using a DSC radio, shipborne 
universal AIS transponder, or INMARSAT ship earth station.
  Self-assigning an MMSI is prohibited.  
How a vessel owner obtains an MMSI depends on whether the ship radio station requires an individual 
license from the FCC.
  A ship station does not need to be licensed individually by the FCC if:  (1) it is 
not subject to the radio equipment carriage requirements of any statute, treaty, or agreement to which the 
United States is signatory; (2) it does not travel to foreign ports; and (3) it does not make international 
  Owners of ship-board radios that do not fall under these categories can obtain MMSIs 
from these designated private registration agents:  BoatUS, Sea Tow International, Inc., Shine Micro, Inc., 
and United States Power Squadrons, Inc.
  For ship radio stations that must be licensed by the FCC, the 
FCC assigns MMSIs through the individual ship station licensing process.
Improper Use of MMSIs
Several common situations, discussed below, have resulted in the transmission of incorrect or duplicative 
Obtaining an Individual License for Certain Ship Radios.  Owners of vessels with ship radios registered 
by private registration agents, and owners of ship radios on vessels registered under a foreign flag, that 
later decide to get individual licenses for those radios from the FCC cannot continue to use the MMSI 
previously issued by the private registration agent or foreign administration.  Instead, those vessel owners 
must use the new MMSI assigned with the FCC license.  In addition, the vessel owner must cancel its 
MMSI issued by the private registration agent. 
Cancellation or Expiration of Ship Radio License. Owners of vessels with ship radios individually 
licensed by the FCC that later decide to cancel the license (or allow it to expire) generally may continue 
to use the FCC-issued MMSI, but must register it with a private registration agent.  Owners of vessels 
formerly registered under a foreign flag that later operate a ship radio station on a vessel registered in the 
United States, however, must obtain a newly issued MMSI. 
Sales of Vessels.  After a vessel is sold or transferred, the new owner may continue to use the MMSI 
associated with the vessel.  For vessels with ship radio stations that had been registered by a private 
registration agent, the new owner must re-register the privately-issued MMSI and the new emergency 
contact information with a private registration agent.  (The new vessel owner is allowed the re-register the 
MMSI with any private registration agent.  However, if the new vessel owner is using a different private 
registration agent, the new owner must cancel any duplicate MMSI issued by the previous owner’s private 
registration agent.)  For vessels registered by the FCC, the new vessel owner may continue to use the 
FCC-issued MMSI by requesting that MMSI when filing the application Form 605 – Schedule B and 
entering the requested MMSI in item 13.  Similarly, purchasers of used equipment must ensure that the 
47 CFR § 80.103(b).
Under 47 U.S.C. § 307(e), the FCC can adopt rules licensing a class of radio stations, so that those stations no 
longer need to be licensed individually.
47 CFR § 80.13(c).
Contact information for the four private registration agents can be found in Commission Announces Agreements 
with Shine Micro, Inc., and United States Power Squadrons, Inc., and Termination of Agreement with MariTEL, 
Inc., Regarding Assignment of Maritime Mobile Service Identities (MMSIs), Public Notice, 22 FCC Rcd 7329 (WTB 
MD 2007), and at
We direct parties interested in applying for a ship station licensing process to the FCC’s Universal Licensing 
System (ULS), which can be found at 
3correct MMSI is programmed into the device before it is used on board a different vessel.  In no case 
should the seller use the old MMSI on a different vessel if the buyer will continue using that MMSI.
Testing of AIS Equipment on Land.  AIS land stations such as research facilities, marine electronic 
maintenance and repair shops, and other entities that test AIS equipment on land frequently undertake 
testing without proper authorization, often using an MMSI that has been fabricated by the testing entity 
(e.g., 123456789).  AIS land stations must obtain a maritime support station license to authorize any on-
land test transmissions.  The maritime support station may, for purposes of on-land testing of AIS 
equipment, use either the MMSI assigned to it or the MMSI assigned to the ship station with which the 
equipment is associated.  Applicants for a maritime support station license may obtain an MMSI for their 
on-land test transmissions by attaching a request for an MMSI as an exhibit to the application Form 601.
Penalties for Use of Inaccurate MMSIs
Use of inaccurate MMSIs is a violation of FCC rules, with potential impact upon safety of life and 
property.  Improper use of an MMSI with AIS hinders its usefulness as a navigation tool for collision 
avoidance, and decreases the Coast Guard’s awareness of vessels in the maritime domain, especially 
vessels approaching U.S. ports.  Violators may be subject to the penalties authorized by the 
Communications Act, including monetary penalties as high as $16,000 for each violation.
  Your radio 
equipment may also be seized and forfeited to the U.S. Government.
Need more information?  To file a complaint, visit or call 1-888-CALL-FCC.  
For additional information regarding enforcement of the marine radio rules, visit the websites below or 
email  Media inquiries should be directed tomailto: Will Wiquist at (202) 418-
0509 or  
? For information related to ship station licenses, obtaining an MMSI, and licensing of marine radio 
stations, please visit the FCC website at
? For information regarding the proper use of MMSIs by commercial and recreational vessels see 
Wireless Telecommunications Bureau Reminds Mariners Regarding Correct Use of Maritime 
Mobile Service Identity (MMSI) Numbers, Public Notice, 27 FCC Rcd 15260 (WTB MD 2012), 
? For more information on MMSIs, please visit the Coast Guard website at 
? For more information on AIS, please visit the Coast Guard website at 
To request materials in accessible formats for people with disabilities (Braille, large print, electronic files, 
audio format), send an e-mail to or call the Consumer & Governmental Affairs Bureau at 
202-418-0530 (voice), (202) 418-0432 (TTY).  You may also contact the Enforcement Bureau on its TTY 
line at (202) 418-1148 for further information about this Enforcement Advisory, or the FCC on its TTY 
line at 1-888-TELL-FCC (1-888-835-5322) for further information about the marine radio rules. 
Issued by:  Chief, Enforcement Bureau
- FCC -
47 C.F.R. § 1.80(b)(7).  See also 47 U.S.C. § 501(identifying possible criminal sanctions, including imprisonment).
47 U.S.C. § 510.