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The Coast Guard accepted the final tower in the Rescue 21 system Oct. 10, 2017 completing a more than 20-year design and installation process that improved search and rescue communications infrastructure throughout the U.S. and its territories.

The Coast Guard conditionally accepted and began operating the completed Rescue 21 system in the Western Rivers region in June 2017. The Western Rivers System provides coverage for parts of the Mississippi, Missouri and Ohio Rivers and their major tributaries.

The Coast Guard conditionally accepted and began operating the Rescue 21 system in the Upper Mississippi sector, which covers portions of the Mississippi, Illinois, Missouri and St. Croix rivers and extends across seven states, May 2, 2017.

Rescue 21 for Boaters


Rescue 21 will increase the Coast Guard’s ability to respond to distress calls in the coastal zone. However, you can help us improve response time by using a marine-band VHF-radio equipped with digital selective calling (DSC).

Why use a radio equipped with DSC?

With the push of a button, your DSC radio will send an automated digital distress alert containing your Maritime Mobile Service Identity (MMSI) number, position, if interfaced with GPS, and the nature of distress to other DSC-equipped vessels and rescue facilities. As a result, the Coast Guard is able to respond more quickly and to more accurately identify the location of the distress call. For more information on DSC and how to send alerts and test your equipment, check out the Coast Guard’s Navigation Center website.

Get your MMSI number

To obtain and register your MMSI number, check out the Boat U.S. and Sea Tow MMSI programs. Both have been certified by the Federal Communications Commission and the Coast Guard.

Vessel Safety Check

The Coast Guard Auxiliary is available to help local boaters ensure that their radios are in good working order. Click here to schedule a vessel safety check in your local area. Examiners also can educate boaters on the importance of properly connecting Global Positioning System equipment to your VHF-radio to ensure a DSC transmission provides proper position information.

Sending a DSC message directly to Coast Guard Sectors

DSC distress alerts will be received by the Coast Guard when Rescue 21 is fully operational in your area. Listed below are the MMSI numbers for Coast Guard sectors and groups that have Rescue 21. These numbers can be used to send a DSC message directly to Coast Guard units.

Rescue 21 VHF DSC MMSI Numbers

Sector/Group MMSI
Baltimore 003669961
Boston 003669901
Buffalo 003669960
Charleston 003669907
Corpus Christi 003669916
Delaware Bay 003669905
Detroit 003669930
Guam 003669994
Hampton Roads 003669922
Honolulu 003669939
Houston/Galveston 003669915
Humboldt Bay 003669909
Jacksonville 003669891
Key West 003669918
Lake Michigan 003669933
Long Island 003669931
Los Angeles/Long Beach 003669912
Miami 003669919
Mobile 003669914
New Orleans 003669908
New York 003669929
North Bend 003669911
North Carolina* 003669906
Columbia River 003669937
San Diego 003669913
San Francisco 003669926
San Juan 003669992
Sault Ste Marie 003669935
Puget Sound 003669938
Southeastern New England 003669928
St. Petersburg 003669917
All USCG coast stations in the United States 003669999
International MMSI number designated for all coast station 009990000


Rescue 21 enables the Coast Guard to execute its search and rescue missions with greater agility and efficiency.


  • Improved information sharing and coordination with the Department of Homeland Security and federal, state and local first responders
  • Geographic display to assist in identifying hoax callers, conserving valuable response resources
  • Digital-selective calling support, which allows mariners in distress with DSC-equipped radios to transmit, at the push of a button, their exact GPS position and vital vessel information to the Coast Guard and other DSC-equipped vessels
  • Improved clarity, recording and playback capabilities for all communications
  • Simultaneous monitoring and relaying of information over multiple radio frequencies
  • Portable tower communications equipment for use during emergencies and natural disasters
  • Automated transmission of urgent marine information broadcasts