Almost all ISPs went through a scheme setup by British Telecom - you could either have free internet but you paid for your calls, or you could pay for your internet, and have access via a freefone number - so effectively flat-rate.
But the flat-rate option disconnected after two hours, on the dot. Which was hugely frustrating because we had a voicemail variant that was hosted by the telco, and let you know you had messages waiting by pulsing the dialtone. And my modem did not recognise the pulsed dialtone as a valid dialtone, and refused to connect until we called the number and marked them read.
Which lead to one of my most UK-centric retro stories. I tried to connect to the internet, and it refused to dial. I blew away my wvdial config, and it refused to dial. I blew away my ppp config, and it refused to dial. I grepped / for the error message and it didn't exist. I ended up blowing away my OS (and accidentally installing onto the wrong drive, and blowing away everything non-OS too), and it still wouldn't dial.
So I dragged the modem & extension cord to my mother's PC, and shot off a mail to my preferred mailing list (one hosted by John @ linuxemporium, my preferred source of mail-order distros), and swiftly received the response that in order to be certified by BT to operate on their network, one of the rules equipment had to obey was to refuse to redial the same number x many times. And that all I needed to do was power-cycle the modem. Which I'd done by dragging it upstairs to my mother's PC. And my own machine had been wiped twice over needlessly.
Aside, there was a lady named Helen on that mailing list who knew everything about everything, and is everything I aspire to be today. She had opinions on which harddrives best survived salt/sea air, and why they weren't deathstars. Just an incredible amount of lived experience. I miss mailing lists.