>there's no simple one to one mapping Why not: you can count the letters A=01, Z=26 and use that, use 2 digits each time, numbers start w/ 3 (e.g. 0=30, 9=39)

>there's no simple one to one mapping Why not: you can count the letters A=01, Z=26 and use that, use 2 digits each time, numbers start w/ 3 (e.g. 0=30, 9=39) That's inefficient but trivial to understand, then there is the T9 which use to be the very standard for the first mobile phones. It's language dependent obviously for prediction but pretty cool, too. Then there is Morse code which would be implement as well. Overall I'd not call the 'demo' impressive at any form.