I operated something like this around 2005 in a big hotel building (~400 bedrooms and various offices) with a dinky internet connection and no wifi yet (very thick walls, up in the mountains, limited budgets...).

So I built a dial-up pool on an internal number (this place had its own PBX with ~500 phone lines) hooked to a Debian box, served by a bunch of USR Courier modems. Good times :)