Save My Sugar by Antonio Ospite http://savemysugar.ao2.it/
What
SaveMySugar is an experiment about sending short messages using the phone ring as a covert channel.
Another classic example of using a covert channel is Port knocking.
SaveMySugar uses the distance between phone calls to represent Morse code symbols.
The idea of using phone rings to send information is not new, it was already used by the very cool xringd project by Angelo Haritsis.
Someone else also proposed it on Half Bakery.
However there seems to be no implementation of the technique for exchanging text messages, and that's what SaveMySugar is about.
The name SaveMySugar was born as a take on the price of Short Message Service which is quite high, see The True Price of SMS Messages, and it is also a reference to the distress signal Save Our Soul (SOS) used in Morse communications.
Why
There are several reasons why you may want to try SaveMySugar:
Just because you can, and it is fun.
It is a possible way to send a short message for free.
It's beautifully slow.
Why not
SaveMySugar has some limitations:
It's awfully slow.
Phone rings keep the line busy.
On mobile phones a ring uses a lot of battery, and battery is a precious resource.
On mobile phones a lot of fake calls will pollute you calls log.
On mobile phones a malicious recipient can make you pay at every ring!
If everyone used it, it might end up like this.
However it is still fun nonetheless.
Where
You can find a prototype implementation written in python called python3-savemysugar.
There is also a prototype Android app SaveMySugar-0.1-debug.apk, its source code is in the android-savemysugar repository.
Contact Antonio Ospite if you want to discuss about porting SaveMySugar to other platforms.
Who
From an idea by Corrado Rubera. SaveMySugar was realized by Antonio Ospite.