After his recent article on How to Successfully Hail on the VHF, some of our readers requested Douglas follow up with an article on the topic of DSC calling.
Did you know that you have a phone number on your VHF radio, and your VHF radio can behave like a telephone? It is called, “Digital Signal Calling” (DSC).
Digital Signal Calling
With DSC you can call another station directly without hailing them first. Your phone number is your MMSI; the number you programmed into your radio when you installed it, and then forgot about. These days, with AIS, it is very easy to see the names of the boats who are around you, and to see their phone number, their MMSI.
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- Checking the MMSI number
Trying the DSC CALL function
On your VHF, find and then try the DSC CALL function:
- Select “individual call”
- Input the MMSI of the boat you want to reach
- Select the channel you want to use and press send
The other party, the boat you are calling, will hear their radio ring like a phone. If they know or figure out what that noise is all about, they can answer you, and voilà, you are talking directly on the station you selected. No hailing. No channel switching.
Most of the times I try this, the other boat doesn’t answer. They must think; Oh this has to be a mistake. I don’t know what this is, this can’t be for me. They ignore or dismiss it. Hopefully from this article, more cruisers will learn the advantages of DSC and begin to use it.
Tips for dialing the number
Dialing the number can be a bit of a pain, but after some practice, you can get it in there pretty quickly (Hint: Use the tuning knob). If you call another boat frequently enough, you can also add them to a directory. Then you don’t have to dial their number every time you want to call them.
MMSI Numbers
As an interesting aside, the first three digits of an MMSI number identify the country where the MMSI was issued according to the ITU Table of Maritime Identification Digits.
Here are some examples:
- 261 is Poland
- 263 is Portugal
- 276 is Estonia
- 310 is Bermuda
- 316 is Canada
- 338, and 366 to 369, are USA
370 to 374 are Panama
226 to 228 are France
Give DSC a try
So there is something you can do with a friend or buddy boat some time – try out Digital Signal Calling (DSC). Practice how to call. Practice how to answer. DSC is very handy for having a casual communication with another boat without very publicly hailing them.
Have you tried DSC calling before? Let us know down in the comments if you’ve found it useful, or are planning to give it a try!
By Douglas Lovell
After a professional life in computer science and aeronautics, and some time spent living in Uruguay, Doug bought the sailboat, Brisa in December 2020, in La Paz, Mexico. Since then he's sailed over 7000 nautical miles, taking the long way back to his adopted home.
