"Randall Stross has just published a sobering article in The New York Times about how the four major US wireless carriers don't want anyone to know the actual cost structure of text message services to avoid public outrage over the doubling of a-la-carte per-message fees over the last three years.

The truth is that text messages are 'stowaways' inside the control channel — bandwidth that is there, whether it is used for texting or not — and 160 bytes per message is a tiny amount of data to store-and-forward over tower-to-tower landlines. In essence it costs carriers practically nothing to transmit even trillions of text messages.

When text usage goes up, the carriers don't even have to install new infrastructure as long as it is proportional to voice usage. This makes me dream of the day when there is real competition in the wireless industry, not this gang-of-four oligopoly."

http://www.nytimes.com/2008/12/28/business/28digi.html