SOS is the best-known Morse code signal in the world: three short, three long, three short. It is sent as a single unbroken pattern, ...---..., without the usual gaps between letters, so it cannot be mistaken for anything else.
SOS was adopted as the international distress signal at the International Radiotelegraph Convention in Berlin in 1906 and came into force in 1908. It was chosen because the pattern is simple, distinctive and easy to recognise even through noise. The popular phrases “save our souls” and “save our ship” were made up later to fit the letters; the signal was never short for anything.
Sending SOS without a radio
- Light: short and long flashes with a torch or phone light. Use the flash option on this page to see the timing.
- Sound: short and long blasts on a whistle or horn, or knocks on a wall or pipe.
- On the ground: SOS laid out in large letters with stones, logs or clothing can be seen from the air.
Only use SOS in a real emergency. If you are in danger and have a phone signal, call the emergency number for your country first (999 or 112 in the UK, 911 in the USA and Canada, 112 across Europe).
Questions and answers
Does SOS stand for save our souls?
No. The letters were chosen for their simple, distinctive pattern. Phrases like save our souls were invented later to fit them.
Why is SOS sent without gaps?
Sending it as one continuous pattern makes it a single, unmistakable signal rather than three separate letters.