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.
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.