May 2009 - Mobivity

Ever Wonder Why SMS is Limited to 160 Characters?

Posted by | General, SMS | No Comments


This is a great article covering how 160 character became the number we are all forced to live with today. You can read the whole thing at LA Times

In 1985 Friedhelm Hillebrand a communications researcher and a dozen others had were laying out the plans to standardize a technology that would allow cellphones to transmit and display text messages.  Because of tight bandwidth constraints of the wireless networks at the time — which were mostly used for car phones — each message would have to be as short as possible.

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."

As chairman of the nonvoice services committee within the Global System for Mobile Communications (GSM), a group that sets standards for the majority of the global mobile market, he pushed forward the group’s plans in 1986. All cellular carriers and mobile phones, they decreed, must support the short messaging service (SMS).

Looking for a data pipeline that would fit these micro messages, Hillebrand came up with the idea to harness a secondary radio channel that already existed on mobile networks.

This smaller data lane had been used only to alert a cellphone about reception strength and to supply it with bits of information regarding incoming calls. Voice communication itself had taken place via a separate signal.

"We were looking to a cheap implementation," Hillebrand said on the phone from Bonn. "Most of the time, nothing happens on this control link. So, it was free capacity on the system."

Initially, Hillebrand’s team could fit only 128 characters into that space, but that didn’t seem like nearly enough. With a little tweaking and a decision to cut down the set of possible letters, numbers and symbols that the system could represent, they squeezed out room for another 32 characters.

Still, his committee wondered, would the 160-character maximum be enough space to prove a useful form of communication? Having zero market research, they based their initial assumptions on two "convincing arguments," Hillebrand said.

For one, they found that postcards often contained fewer than 150 characters.

Second, they analyzed a set of messages sent through Telex, a then-prevalent telegraphy network for business professionals. Despite not having a technical limitation, Hillebrand said, Telex transmissions were usually about the same length as postcards. 

Just look at your average e-mail today, he noted. Many can be summed up in the subject line, and the rest often contains just a line or two of text asking for a favor or updating about a particular project.

But length wasn’t SMS only limitation. "The input was cumbersome," Hillebrand said. With multiple letters being assigned to each number button on the keypad, finding a single correct letter could take three or four taps. Typing out a sentence or two was a painstaking task.

Later, software such as T9, which predicts words based on the first few letters typed by the user, QWERTY keyboards such as the BlackBerry’s and touchscreen keyboards including the iPhone’s made the process more palatable.

But even with these inconveniences, text messaging took off. Fast. Hillebrand never imagined how quickly and universally the technology would be adopted. What was originally devised as a portable paging system for craftsmen using their cars as a mobile office is now the preferred form of on-the-go communication for cellphone users of all ages.

Obviously Hillenbrand was dead on. Text messaging has been a major boom around the world and here in the US where mobile users sent an average of 357 texts per month in the second quarter of 2008 versus an average of 204 calls.

If you are wondering if the guy who helped revolutionize SMS became rich, unfortunately for him he did not. But thanks to Hillenbrand I was able to start-up a Mobile Marketing company with my partner Greg and I can let my wife know when I am running late for dinner.

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