

Missed call - jmduke
http://en.wikipedia.org/wiki/Missed_call

======
chromano
I wonder if the success of that "yo" app is based on this concept (even though
I think using missed calls are way more effective than using the internet).

------
lewispollard
It's interesting that SMS piggybacks off the handshake part of connecting a
phone call - making it actually less data intensive than utilising missed
calls, I assume - yet phone companies make a killing on SMS packages and
costs.

