come to think of it, i don't think there were any private multiline boards in my local toll-free calling area.

it was only packet switched commercial services and shell based internet at the libraries/university.

The only multi-line one I remember vividly was running MajorBBS. The inter-user chat was especially vulnerable to sending RIP commands as it didn't filter them out.

"My user number? Why, 99E99, of course."