56k modem and network not dropping when modem switched off

[Motor]

I'm using Fedore Core 4 and accessing the internet via a 56k modem. For the last couple of years I've used a script to get pppd up and running and it's worked without any problems.

However, over the last week or so something seems to have changed. When I switched off the external modem, the network used to go down. Now though, switching off the modem does not bring the network down -- and the /etc/ppp/ip-down script is not executed. Why? Has an update from Red Hat broken this behaviour?

Besides installing updates, the only thing that has changed is that I installed NetworkManager to see what would happen -- and then uninstalled it. Did that installation alter a setting?

Thanks for any information.

[Motor]

Never mind -- I just discovered that the serial port lead in the back of the machine was not quite in properly (it had gradually slipped out... that'll teach me to screw them in)... weird, everything else about the modem was working correctly. The disconnected pin(s) must have been the one(s) that signal a disconnect.

Anyway, it's working now.