Back in the 80s and 90s, packet radio linked amateur radio stations together. In fact, it goes back even further than this — the use of TCP/IP on amateur radio preceded the appearance of the public Internet. Anyway, whereas at the time most people were getting their data using modems and telephone lines, radio amateurs were experimenting with terminal node controllers (TNCs) and radio waves.
The TNC takes a chunk of data, splits it into packets, and sends it over VHF/UHF, and a TNC on the other end decodes, error-corrects and delivers it. TNCs are also digipeaters, repeating traffic for a further-flung station. An adaptation of the AX.25 protocol is used to handle many TNCs using one frequency. The result is an error-corrected, transparent and automatic network. Such networks are still in use; APRS, a protocol to share tactical information and short messages, is built on top of packet.
Some TNCs had a feature whereby you could leave messages for their owners. Bulletin board software began to develop partly out of this, allowing one-to-one message exchange and posting on forums, real-time chat, distributing news and data, and whatever the operators of the BBS want to offer. The scene may be quieter, but it isn’t dead. Ten or so packet BBSs still exist in the UK.
Several of us on the Amateur Radio IRC channel expressed an interest in setting up and managing a BBS, perhaps even on a local packet network. We’ve been talking about what other fun features beyond message passing we could implement, like Richard Osgood's BBS that allows users to play Zork. We might be able to reach quite a lot of people from a central London location. However, we’d need somewhere with decent coverage and we’d also need a full license to run an unattended node. Furthermore, to repeat or rebroadcast other peoples’ messages we’d need a Notice of Variation.