Sending Text Messages Cheaper Than You Think

TEXT messaging is a wonderful business to be in: about 2.5 trillion messages will have been sent from cellphones worldwide this year. The public assumes that the wireless carriers’ costs are far higher than they actually are, and profit margins are concealed by a heavy curtain.....

Perhaps the costs for the wireless portion at either end are high — spectrum is finite, after all, and carriers pay dearly for the rights to use it. But text messages are not just tiny; they are also free riders, tucked into what’s called a control channel, space reserved for operation of the wireless network.

That’s why a message is so limited in length: it must not exceed the length of the message used for internal communication between tower and handset to set up a call. The channel uses space whether or not a text message is inserted.

Srinivasan Keshav, a professor of computer science at the University of Waterloo, in Ontario, said: “Messages are small. Even though a trillion seems like a lot to carry, it isn’t.”