An Interesting protocol to communicate train delays using missed calls :)

I can across a new article in TOI [1] that talks about how passengers on the Delhi-Palwal and Delhi-Rewari routes has been giving halfhourly updates so as to notify train delays

1. http://epaper.timesofindia.com/Default/Scripting/ArticleWin.asp?From=Archive&Source=Page&Skin=TOINEW&BaseHref=CAP/2010/01/24&PageLabel=12&EntityId=Ar01201&ViewMode=HTML&GZ=T

An Excerpt from the article, about how the communication works.
A commuter at the station sends a missed call to another passenger travelling on the train, asking her for an update on the train.‘‘If the train is 10 minutes late, the passenger repliles with one missed call. If there is a delay of 20 minutes, there are two missed calls. Three missed calls mean the delay is for over 20 minutes.
If the call is disconnected within five seconds even as the passenger on the platform makes the call, it signals that the train has been cancelled. If it gets a ‘busy mode’ response, the message is that the train is over an hour late. If you receive one missed call and then receive another missed call a few moments later, it is presumed that the train is delayed by over an hour.