SMS usage in Aus has grown at an explosive rate since inter-carrier SMS was switched on. (Like, how dumb was it to not be able to send SMS from one company to another. Duh.)
It's so popular, Telstra, the no-we're-not-acting-like-a-Monopoly, has jacked up the price to 25c per message, because of 'heavy usage' or somesuch bollocks.