Avoid reinstalling modem when turning it on after boot
When using a dialup modem with win2k and have booted without starting the modem the modem will be unavailable unless you do a scan for new hardware or reboot the machine and makes sure the modem is on.
The modem can be made permanent by going into Phone and Modem Options in the Control Panel and remove the current modem. Then Add the modem again. During the reinstall it will ask you if it should detect the modem for you, answer no. Now you will be shown a list of modems, there you can find the modem you had installed before, unless you have the modem drivers on a disk.
This trick only works when you turn the modem on after booting into Win2k, if having the modem turned on and booting into win2k the modem will be redetected, if it has been installed as said above.