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Why Text Messages Are Limited To 160 Characters

Posted by Soulskill on from the how-many-characters-do-you-really-need dept.

The LA Times has a story about Friedhelm Hillebrand, one of the communications researchers behind efforts to standardize various cell phone technologies. In particular, he worked out the 160 character limit for text messages. "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 ... 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. ... 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.

5 of 504 comments (clear)

  1. Re:no, its because 160 by Anonymous Coward · · Score: 5, Informative

    it also happens to be precisely 2 lines of text on a good old 80 character wide terminal.

  2. Re:no, its because 160 by SgtPepperKSU · · Score: 5, Informative

    is the bastard offspring of the union of the hexdecimal and the decimal, literally 0xF*10

    fixed that for you

    Are you joking?
    0x10*10...

  3. Getting 160 chars in 128 bits. by pavon · · Score: 5, Informative

    For those that were wondering how they got 160 characters into 128 bytes (6.4 bits/char), they didn't. The increased the length of the frame to 140 bytes, which is is 160 characters using a 7 bits/char. Curiosity forced me to look this up, expecting to find some snazzy compacting algorithm for a non power-of-two alphabet.

  4. Re:BINGO! by OlRickDawson · · Score: 5, Informative

    http://en.wikipedia.org/wiki/Punched_card Punch cards predate the computer, because they were used in loom machines to generate paterns. The punch cards were later used for statistical purposes. IBM was already selling statistical machines that used the punch cards before the computer. The reason that IBM was able to grab the market instead of Univac, is because IBM's computers was compatible with the punch cards that the corporations already had.

    --
    Ol' Rick Dawson had a farm EIEIO
  5. Re:I'll Be Damned by nomorecwrd · · Score: 5, Informative

    Actually, SMS is like a "stowaway" of a signal your cell must receive from time to time.
    So the "real" cost of a SMS is 0.000000.

    This is a broadly known fact.

    Years ago, here in Chile anyway, SMS where free of charge.
    Now is pure profit. (about 8ct/SMS at current exchange)