I'm backwoods camping next week, and we have 25 people spread out over three sites. I was thinking it would be funny to bring some old rotary dial phones and some sort of way of hooking them up, and then just have that as the intercom between sites for when dinner is ready or whatever.
It's next week, so unlikely to happen and I'm not sure what technology I would need to make it all work. Something like Lora plus a way to make the phones work.
Chaining together a few WiFi routers and running a local IRC server with ergo could work well (so get everyone on the same WLAN even if no Internet). There is also Briar chat on mobile. Maybe Mumble for voice could work. I'd look for routers on Craigslist or eBay that are under $20 each and have OpenWrt support. Have had good luck with the Netgear R6220 in the past, but there could be other good options as well.
My entire community use it. We set channel and CTSS to our area code so people can remember it. I also have intercoms that use it.
Outside of the legal realm there are also ham radios that are either easy to frequency unlock or are pre-unlocked to do FRS+DMR for encryption though I would never do this outside of a dummy load.
Less fun but you can also run OpenBTS or Yate to get your own GSM network. Probably illegal but nobody's gonna care in the woods.
Back in the day we would "find" spools of phone cable and string them between houses. If you found that much cable you could definitely wire up a few miles of woods.
Regular walkie talkies + VOX + headset re-assembled into the phone handset ? Make the phone hook a switch to cut the mic (err, like it originally did, I guess). It's not elegant but it could be a quick evening's work.
A couple years ago I stayed at an AirBnB and there was an old rotary phone in the kitchen. Unfortunately, I found it was merely placed there as an antique curio and wasn't hitched up with service. I felt a little cheated honestly.
It's next week, so unlikely to happen and I'm not sure what technology I would need to make it all work. Something like Lora plus a way to make the phones work.