Modem is already in use, or is not configured for Remote Access dial out or The port is in use.
1) Verify no other applications that are using the modem. You can open Task Manager to check that by press CTRL+ALT+DEL. Another way to test it is reboot the computer.
2) This behavior may occur when another device with a driver, for example outdated Palm Pilot software, conflicts with the modem.
3) Telephone.ini or unimdm.tsp is missing or damaged.
4) Make sure the modem is setup correctly and may apply SP.
5) Removing and reinstalling it, or apply the new drive may fix the problem.
6) Make sure no two ISDN installed on the same machine and attempt to connect to the same server.