I'd guess it used BRI. PRI would probably have been considered too expensive to justify running to a payphone. My guess is the BRI socket on that payphone is on

I'd guess it used BRI. PRI would probably have been considered too expensive to justify running to a payphone. My guess is the BRI socket on that payphone is only operable when you're not making a call, so the 2x64k BRI line can be assigned to the phone or passed through to that socket. You're working on a user-mode ISDN stack - this sounds extremely interesting! Care to drop me a line? https://www.devever.net/~hl/contact https://www.devever.net/~hl/contact