True, I did think that - since it is a pretty obvious idea that anyone can think of - to use it as a signal to the called party, but was thinking more in terms of India being a less rich country (broadly), so more people may do it here to save money :), since, though it's only a little each time, it can add up if one calls people a lot. On the other hand, India nowadays has very cheap mobile rates compared to many other countries, I've read.