why disconnects?

[Ben Luey <lueyb@gridley.ACNS.Carleton.edu>]

My housemate and I share a modem line between our computers. If he leaves
his computer connected and goes to sleep and I try to connect with my
computer, I can't dial in and his connection stays up. There is no way to
kill his connection short of going into his room and disconnecting his
computer. Yet if I'm online and he tries to dial in, my connection dies
and before it realizes it and redials, his computer has already dialed and
connected. This hardly sems fair. Is there an option in ppp for not
hanging up on line noise and just waiting it out? What causes a connection
to disconnect?

Thanks,

Ben