How to connect to the "Internet" without a provider?

Question

Computer networks

As in the distant 90s, my friend had 386, then there were no providers, we connected via a modem and exchanged messages, how to organize it now, you only need to exchange messages, nothing more.
Made adjustments! How to use a modern telephone network to exchange information between computers using a "dialup" modem and not using the services of modern current Internet providers, respectively, "home" telephone connection is made and the phone itself is working.
Space distances...

Answer 1

then there were no providers, we connected via modem and exchanged messages,

You have used a telephone carrier as a provider.
You take an analog phone line, a couple of modems, and organize it the way it was before.
You can't connect to the internet without an ISP. This is either not the Internet, or you yourself are a provider (one of) with all the consequences.
If you want "without a provider", pull your communication line to it (this will be called Intranet ).
Plenty of options:
The specific implementation depends on the requirements for the communication line, distance and most importantly the budget.

Answer 2

Well, here I see two options, originally from the 90s ...
In both cases, you will need a landline phone and an analog modem - and here is your first challenge - to start a modem under Windows - because BBS was "dialed". In FIDO, they also "dialed", there was ZMH (Zone Mail Hour, Zone Mail Hour - the time when all nodes of the zone should be on call)
- BBS. I don’t know, however, whether it will be possible to get sources or a distribution, for example, Maximus BBS, anywhere now, and I’m not at all sure that it will work under Windows, most likely, Linux and manual assembly will be needed. Set yourself (or a friend) BBS, set up. The one who has a BBS - operator, can correspond from the console. To hang in touch together - you need two numbers, but it will be like a chat.
- FIDO. Either build a network of two nodes using FTN technology yourself, or look for someone who represents the current FIDO (shrunken to microscopic sizes, but still kicking) and take a point - each. Correspondence only offline.
No authentication. No encryption. No anonymity (it is not in FIDO and never was).

Answer 3

And what is the Internet, in this context? A connection method for transmitting information, you can throw a wire, use radio stations, transmit Morse code with a spotlight, use the telephone network by voice or via modem, tap in code or Morse code, send by mail or send a messenger with a flash drive.