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Let's imagine a closed-system (let's say "City under a dome" controlled by benevolent corporate overlords) where there's no Internet because it's not allowed. The infrastructure exists, there are satellites out there, but they're tightly controlled so that no Internet is able to form inside said dome. Now let's allow for there to be a population that lives outside the dome with limited access to resources. They can't control the satellites or make use of existing infrastructure (except perhaps by bootlegging or hacking their way in). What infrastructure would be necessary for them to have rudimentary devices like cell phones that allow strictly for texting between members of the same network?

EDIT: To be clear, I understand that satellites are not used in cellphone communications and that the Internet is unrelated to communications of this kind; I just needed to specifically rule it out as an option in coming up with some way to communicate between devices. So if repurposing existing towers that may have once be used for cell phone communications is sufficient, that's helpful to know; in what I'm writing, the people who live in this area outside the "dome" (it's not a dome, just using this verbiage for illustrative purposes) use messenger devices like pagers to text to each other, so I just wanted some speculation on what technology they might be using. My question is not ridiculous, so please be civil in your speculations. For example, a couple suggestions were ham radios or pagers, using bluetooth, or optics/lasers. These are the kind of answers I was looking for.

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    $\begingroup$ Something like a pager network could be minimum level of technology to relay simple text messages. $\endgroup$ Dec 9, 2018 at 16:48
  • $\begingroup$ Although I'm glad you found my answer helpful, it's usually best to wait before accepting an answer, to allow others time to weigh in. $\endgroup$
    – Cadence
    Dec 9, 2018 at 17:25
  • $\begingroup$ My mistake, I'll uncheck it until there are more answers $\endgroup$
    – alkah3st
    Dec 9, 2018 at 18:20
  • $\begingroup$ What's the "they" and "them" you refer to in the last two sentences of the question? The people inside the dome (where Internet is prohibited), or the people outside the dome (who have "limited access to resources")? Why do you feel that Internet is a prerequisite for "texting"? The question you're asking is probably answerable, but I get the distinct feeling that what we're seeing here is an example of a XY problem. $\endgroup$
    – user
    Dec 9, 2018 at 18:35
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    $\begingroup$ I am absolutely certain that the Short Message Service (SMS) was available long before mobile phones became powerul computers connected to the Internet. Internet-less GSM phones still work to this day. $\endgroup$
    – AlexP
    Dec 9, 2018 at 19:07

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A cellphone network can be used for SMS (Short Message Service). No internet as it is understood today is required for it, and neither are satellites. All it takes is a network of antenna mast to route selective calling between handsets.

Historically, mobile phones and non-mobile internet began to get off the ground separately, only later the bandwidth became available to bring mobile phones into the internet as we know it.

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    $\begingroup$ To add to your last paragraph, something that older users are more likely to already be aware of: The World Wide Web was invented in 1990. The Internet was invented in the 1960s. The first mobile phone was invented in 1917. (SMS itself was invented in 1982, but electrical telegraph systems had existed since the 1750s, so a text-message-like system could - in theory - have been invented before the internet) $\endgroup$ Dec 9, 2018 at 21:47
  • $\begingroup$ //only later the bandwidth became available to bring mobile phones into the internet as we know it.// you make it sound like it happened ages ago when to anyone not still in short pants it was practically yesterday when the most rudimentary internet access began to appear on mobile phones, it's probably only been a decade (maybe less?) & certainly under two decades. $\endgroup$
    – Pelinore
    Dec 10, 2018 at 1:45
  • $\begingroup$ @Chronocidal : the first texts where being sent almost as soon as mobile phones where in relatively common use, just Google it, "when was the first text message sent", the answer will be sometime in the early 90's, the internet was practically all dial up over the phone systems land lines at the time I'm sure, iirc the internet only really became widely available to the public at around the same time, before that you wouldn't have recognized it as the internet we know today & it was only really available to universities. $\endgroup$
    – Pelinore
    Dec 10, 2018 at 2:33
  • $\begingroup$ @Pelinore WAP (that old no-image Mobile Internet for non-smart phones) was introduced in 1999, so "rudimentary internet access began to appear on mobile phones" 19 years ago. Certainly under two decades, but only just $\endgroup$ Dec 10, 2018 at 8:23
  • $\begingroup$ @Pelinore Yeah, the first SMS was sent in 1992 (3rd December: "Merry Christmas") but GSM had started setting everything up a decade before - it just took ages to get the infrastructure in place and turned on (they needed to convince the network providers and the phone manufacturers that it was worth investing in) $\endgroup$ Dec 10, 2018 at 8:30
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You may be confusing internet with websites and apps.

The internet is a network of computers, working on information through layers of protocols.

If your citizens have electronics and radio communication, the only thing keeping them from building their own network is lack of knowledge. Sooner or later someone will build a modem - a machine that translates analogical signals into digital ones, and vice-versa - and then it's just a matter of time until people have a proto-BBS.

You want people to have no network, you keep them from electronics - or you make sure to kill any kid that shows even a slight sign of being an engineering nerd.

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For starters, it's important to note that neither the Internet nor cell phones rely on satellite infrastructure. Cell phones use a radio-frequency connection to local towers that form "cells" of connectivity across an area. The Internet is defined more in terms of communications protocols; how the messages physically get from point A to point B is immaterial, and will usually consist of a mixture of local RF, wired connections, and satellites.

Your outside population has a couple of options in terms of how they communicate. One is to essentially (re)build a standard modern cell network. In essence all this is is a set of radio towers distributed over the area they're operating in. Phones communicate with the towers, and towers communicate with one another to send messages where they need to go. The big limitation is that building towers is a little expensive and quite visible, which might be bad if the government disapproves of what they're doing. Range is highly dependent on terrain but in practice is probably tens of miles at best.

The second option is to have devices communicate directly to one another - basically walkie-talkies, but with text rather than voice. This eliminates the need for centralized towers, but at the cost of range: for a handheld unit, I'd say generally no more than a mile.

A third option is landlines. Smaller, more discreet local transmitters could be connected by wired connections very safely over long distances. The lines will need to be maintained, though, and if discovered by the government they might be tapped or just cut.

If you have more time and clever people than resources, you could optimize your network by bridging all of these technologies; this is mostly down to the software you're using, rather than hardware. Your phones could have the option of connecting peer-to-peer within range rather than via a tower, or connecting via a third unit as a bridge, or even over landlines. Techniques exist for efficiently routing messages across complex, heterogeneous networks; indeed this is basically how the modern Internet works, so a lot of effort has gone into laying the groundwork you'd need to use, just at a smaller scale.

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Amateur radio.

Ham radio has been around for 100 years, and was originally used to send Morse code. Ham radio operators can send messages for hundreds of miles using privately owned radio equipment. Amateur radio has long been a refuge for persons conducting unsanctioned communication or communicating without the use of established communication infrastructure - because it was not built or it has been destroyed in a disaster.

People do send texts via ham radio - apparently in many different ways!

http://www.aprs.org/aprs-messaging.html

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You could have devices that rely on optics to transmit the message, such as the remote controls or combining laser pointers of different colors, an adapted modems .

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  • $\begingroup$ Would that require very short distances between devices? $\endgroup$
    – alkah3st
    Dec 10, 2018 at 4:03
  • $\begingroup$ Our remote controls are designed as a short distance item but with more energy that could be extended indefenetly (it could become dangerous too). The laser pointers have a longer range. $\endgroup$
    – Tomás
    Dec 10, 2018 at 21:07

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