Thursday 7 May 2009

Why SMS are 160 characters long?

If you have ever wondered about the 160 character limitation on traditional text messages, you might be glad to know that it wasn't an arbitrary figure that was plucked out of thin air.

In figuring out the number of characters to be allocated for text messages, alone in a room in his home in Bonn, Germany, Friedhelm Hillebrand sat at his typewriter, tapping out random sentences and questions on a sheet of paper.

As he went along, Hillebrand counted the number of letters, numbers, punctuation marks and spaces on the page. Each blurb ran on for a line or two and nearly always clocked in under 160 characters.

That became Hillebrand's magic number and set the standard for one of today's most popular forms of digital communication: text messaging.

"This is perfectly sufficient," he recalled thinking during that epiphany of 1985, when he was 45 years old. "Perfectly sufficient."

The whole purpose of the SMS was that the messages to be short and precise towards the communication. Also the communications researcher realized that because of tight bandwidth constraints of the wireless networks at the time each message would have to be as short as possible.

Before his typewriter experiment, Hillebrand had an argument with a friend about whether 160 characters provided enough space to communicate most thoughts. "My friend said this was impossible for the mass market," Hillebrand said. "I was more optimistic."

How true he was towards all his optimism when text messaging has become the prevalent form of mobile communication worldwide. The biggest youth market of the world i.e India at the moment are sending more text messages than making calls on their cellphones.

Texting has been a boon for telecomms which lead the generation of healthy revenue for the operators where they can easily charge the customers some 20 to 25 cents a message.

Todays mobile phones offcourse are capable of transparently spreading a lengthier message across multiple text messages albeit at a higher cost to customers on most mobile phone plans.


Anonymous said...

And I thought This is the real reason !!

Transmission of short messages between the SMSC and the handset is done using the Mobile Application Part (MAP) of the SS7 protocol. Messages are sent with the MAP mo- and mt-ForwardSM operations, whose payload length is limited by the constraints of the signalling protocol to precisely 140 octets (140 octets = 140 * 8 bits = 1120 bits). Short messages can be encoded using a variety of alphabets: the default GSM 7-bit alphabet (shown above), the 8-bit data alphabet, and the 16-bit UTF-16/UCS-2 alphabet.[26] Depending on which alphabet the subscriber has configured in the handset, this leads to the maximum individual Short Message sizes of 160 7-bit characters, 140 8-bit characters, or 70 16-bit characters (including spaces).


kartikshradha said...

Thanks for updating my knowledge, doing great, wishes,

Anonymous said...

The father of SMS is not Friedhelm Hillebrand (he just would like to be one).

True father is a modest engineer from Finland - Matti Makkonen.