There is a HUGE market here for someone to create a free texting app that encodes each character in the length of time before the call has been ended (like morse code, but with no dots, only dashes).
The application would abstract the handshake+message delivery away and hopefully would find ways to reliably send a character in hundred milliseconds, instead of seconds.
If the application becomes successful, you would have live with being the one to make carriers the world over to begin charging when a phone BEGINS ringing, instead of a successful connection. (or remove the loophole in another way, like charge on the 3rd attempt.)
Alternatively don't send individual characters, from a single call the user can choose one of 5-10 default messages (preset or mutually-agreed-upon-inadvance) like "OK" "Be there in 5 minutes" "No" etc via the length of a single call using a mobile phone application.
You can have entire conversations via mobile for free :D
> If the application becomes successful, you would have live with being the one to make carriers the world over to begin charging when a phone BEGINS ringing, instead of a successful connection. (or remove the loophole in another way, like charge on the 3rd attempt.)
They could also start messing up your careful timing. Then it would be much harder to convey information.
This sounds like a terrific idea in theory, but I'm not sure if the times can be measured that precisely. I may be wrong, but try calling your landline phone from your cell phone, and you'll see what I mean.
Would you be able to do this at the app level? Maybe I don't know about it enough but I'm thinking you would need to have direct access to the radio to encode the paging signal. Then wouldn't the base station have to understand our different tones so it can preserve them in order to pass them on?
Encode the positive integer (index of the preset message) in the length of the ringing:
1 second before cutting = OK
2 seconds before cutting = Be there in 5 minutes
3 seconds before cutting = No
4 seconds before cutting = ?
5 seconds before cutting = haha
... etc
It would be much easier to do between friends (understand they are sending a message, not phoning you) but a well coded application could disable its vibrate+ringtone on ALL incoming calls by say, 3 seconds and the message can be placed in that window (so the user doesn't accidentally pick it up thinking it's a call).
There are many ways to do it. A well thought out version can become immensely popular.
Oh right! I mistook your original post for a completely different scheme. Don't know why but I was thinking about encoding data in a single call by reencoding the paging signal.
Your idea is much more feasible and actually kinda cool.
Here in Portugal I remember people using "missed calls", particularly some years ago (when calls where much more expensive) with a code: one missed call to say 'yes', two missed calls to say 'no'.
You can make this robust by using a double-SIM phone at either end. If both parties have one, you can easily get two bits per missed call, as there are four ways for Alice to call Bob.
The application would abstract the handshake+message delivery away and hopefully would find ways to reliably send a character in hundred milliseconds, instead of seconds.
If the application becomes successful, you would have live with being the one to make carriers the world over to begin charging when a phone BEGINS ringing, instead of a successful connection. (or remove the loophole in another way, like charge on the 3rd attempt.)
Alternatively don't send individual characters, from a single call the user can choose one of 5-10 default messages (preset or mutually-agreed-upon-inadvance) like "OK" "Be there in 5 minutes" "No" etc via the length of a single call using a mobile phone application.
You can have entire conversations via mobile for free :D