11.16. My university has 42 billion students but only 4 modem lines. Can tip automatically try each line?

Sure. Make an entry for your university in /etc/remote and use \@ for the pn capability:

            big-university:\
            :pn=\@:tc=dialout
            dialout:\
            :dv=/dev/cuaa3:br#9600:at=courier:du:pa=none:
          

Then, list the phone numbers for the university in /etc/phones:

            big-university 5551111
            big-university 5551112
            big-university 5551113
            big-university 5551114
          

tip will try each one in the listed order, then give up. If you want to keep retrying, run tip in a while loop.