An S.O.S. call is an internationally accepted Morse code distress signal. S.O.S. is sent by people on a ship when they are in danger of drowning, but I have read online that it was also used by pilots b4 they have been shot down. I don't think, though, that sailmen or pilots are the only ones who use the S.O.S. signal. Since it is an Intrnationally accepted distress code, anyone stranded and in serious trouble with no way of getting a phone call trough or any other means of communication have to relly on S.O.S.!
This signal can be transmitted in various ways. It can be sent out as an audio tone, along a telephone wire as an electrical pulse, as long or short pulses of a radio signal, or as a visual signal by using a flash light, also it could be as simple as banging on something or making some kind of noise. It is codified as three dots, then three dashes and three dots again. This sequence is without any space between the dashes and dots. The three dots signify the letter S and the letter O is formed by three dashes.
(info on this I got from reading about it on other websites and magazines.)
There are various phrases that are used as a full form of SOS. They are as follows:
Save Our Souls, Save Our Ship, Send Out Sailors, Save Our Sailors, Stop Other Signals and Survivors On Ship.
"Our only hope is that someone hears aor S.O.S. signal in time...".
"Sir, we're getting an faint S.O.S. signal from somewhere in our vicinity."