Tech4all group blog

SMS (short message service) is available in every mobile phone, and network operators mostly charge for using sms.There are certain free sms plans, but they offer free sms at a monthly "topup" or "booster pack".

About 2.5 trillion messages will have been sent from cellphones in 2008, and 3.3 trillion messages are expected to be sent in 2009, an estimate by Gartner group.

Lets take a look at what are the costs incurred by the network operators(Airtel,Aircel,Bsnl...) for processing sms. (From NYtimes)

"A text message initially travels wirelessly from a handset to the closest base-station tower and is then transferred through wired links to the digital pipes of the telephone network, and then, near its destination, converted back into a wireless signal to traverse the final leg, from tower to handset. In the wired portion of its journey, a file of such infinitesimal size is inconsequential. 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."

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.  "

Cost of sending an SMS is almost nothing, yet the network operators charge upto .50rs or 1re per sms , depending on the plan. Consider it along with the fact that 2.5trillion messages are sent last year, that will make a fortune for the telecom companies.