[telecom] How SMS works

The surprisingly complex journey a text message takes every time we hit 'send.'

By Scott B. Weingart

My leg involuntarily twitches with vibration - was it my phone, or just a phantom feeling? - and a quick inspection reveals a blinking blue notification. "I love you," my wife texted me. I walk downstairs to wish her goodnight, because I know the difference between the message and the message, you know?

It's a bit like encryption, or maybe steganography: anyone can see the text, but only I can decode the hidden data.

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Reply to
Harold Hallikainen
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This is where it began, seventy years ago at Western Union:

Plug-and-jack switching:

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Push button switching:

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There are a long series of articles in WUTR describing the development and implementation of their automated switching systems. While technically sound, economically they were a failure. In the 1950s, the Bell System developed a direct-dialed carrier long distance network that allowed for cheap telephone calls. WU's network was labor intensive. Thus, it became cheaper and easier to phone than send a telegram, and WU's telegraph business took a serious decline.

Reply to
HAncock4

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