The text message was not designed to be a communication medium. It was a diagnostic channel, added to the GSM standard because there was spare room in the signalling system, and nobody involved expected the public to use it.
Forty years later it is still the only messaging format that reaches every phone on earth.
160 characters, decided over a typewriter
The limit that shaped how a generation writes came from Friedhelm Hillebrand, a German engineer working on GSM standards. In 1985, sitting at a typewriter at home, he typed out random sentences and questions and counted the characters. Almost all of them came in under 160.
He cross-checked the intuition against postcards and telex messages — both, he found, tended to fit comfortably in that range. His conclusion, reportedly delivered to a sceptical committee, was that 160 characters was “perfectly sufficient”.
The engineering constraint made it convenient: SMS was designed to travel in the signalling channel that phones and towers already used for control messages — checking signal strength, managing handovers. That channel had a fixed slot of 140 bytes going spare. At 7 bits per character using a reduced alphabet, 140 bytes holds exactly 160 characters.
So the number is the intersection of a spare 140-byte packet and one engineer’s home typing experiment. Both halves are essentially arbitrary, and both are still with you every time your message splits in two.
The first text message
On 3 December 1992, a 22-year-old test engineer named Neil Papworth sent the first SMS from a computer on the Vodafone network in the UK to Richard Jarvis, an executive at a company Christmas party. It said:
Merry Christmas
He typed it on a PC because handsets could not yet send texts — only receive them. Phones capable of composing an SMS did not arrive until 1993, and the feature was regarded as marginal for years afterwards.
Nobody expected it to take off
Carriers built SMS as an operational tool. There was no billing system for it initially, because nobody imagined charging for something so peripheral.
Then two things happened that no one planned.
Prepaid mobile arrived, and with it a large population of teenagers with tight budgets. A text cost a fraction of a call, and the 160-character limit that engineers saw as a constraint became a game. Compression became a subculture — c u l8r, gr8 — which adults promptly decided was destroying literacy.
The interconnect opened. Until 1999 you could generally only text people on your own network. Once carriers allowed cross-network messaging, the addressable population became everyone with a phone, and volume grew explosively.
By 2010, around 6.1 trillion texts a year were being sent. SMS became one of the most profitable products in telecoms history — an accidental one, sitting in spare capacity, at margins that were close to pure profit.
What was bolted on later
The original design was deliberately minimal, and everything since has been an addition:
MMS (2002) added pictures and, almost incidentally, group threads. When your message to several people becomes a shared conversation, that is MMS doing a job SMS never had a concept for — SMS to ten people is simply ten separate messages. This distinction is still the source of the most common group texting mistake.
Concatenated SMS allowed messages over 160 characters by splitting them into parts with a header for reassembly. Which is why a long message can cost you three.
Unicode support let messages carry accented characters and other scripts — at 16 bits per character rather than 7, dropping the limit from 160 to 70. That trade is why one emoji can triple your bill.
RCS, from the 2000s onward, is the attempt to replace SMS with something modern: read receipts, typing indicators, proper groups, high-quality media, running over the internet. Google pushed it for years; Apple added support in iOS 18. It is genuinely better, and it still falls back to SMS whenever both ends do not support it — which is the whole point.
Why it refuses to die
WhatsApp alone carries vastly more messages per day than SMS now. And yet:
It needs nothing. No app, no account, no internet connection, no friend request. A phone number is the entire prerequisite, which makes SMS the only channel that reaches a list of customers who have nothing in common but having given you a number.
It arrives. No inbox, no algorithmic feed, no promotions tab. This is why SMS open rates remain far above email, and why banks, airlines, delivery companies and doctors’ surgeries still use it for anything that genuinely must be seen.
It is universal. Every phone made in the last thirty years can receive a text. No other digital channel is close.
The security model is another story: SMS was designed in an era with different assumptions, and using it as a second authentication factor has known weaknesses. But for the job of getting a short message to a known human being, the 140-byte packet from 1985 has proved remarkably hard to replace.
Questions people ask
Why are text messages limited to 160 characters?
Because SMS was designed to fit in a spare 140-byte slot in the GSM signalling channel, which holds 160 characters at 7 bits each. Friedhelm Hillebrand had already concluded from typing tests and postcards that 160 was enough.
What was the first text message?
“Merry Christmas”, sent by Neil Papworth on 3 December 1992 over the Vodafone network — from a computer, because handsets could not yet compose texts.
Why do accented characters and emoji shorten my message?
They require 16-bit Unicode encoding rather than the 7-bit GSM alphabet, which drops the per-message limit from 160 characters to 70.
Is SMS being replaced by RCS?
Gradually. RCS is better in every technical respect and now works across iPhone and Android, but it falls back to SMS whenever either end does not support it — so SMS remains the universal floor.
Why do businesses still use SMS?
Because it reaches everyone with no app, no account and no internet, and because it gets read. For anything that must actually be seen, nothing else has the same reach.