Microsoft KB Archive/102659

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NT Err Msg: Error 633: The Port Is Already in Use… with RAS

Article ID: Q102659

The information in this article applies to:
- Microsoft Windows NT operating system, version 3.1 - Microsoft Windows NT Advanced Server, version 3.1

When trying to use the Remote Access Service (RAS) with Windows NT, you may receive the following error message:

Error 633: The Port is Already in Use or is not Configured for Remote Access.

Several scenarios can cause this error message:

  • Either the remote machine or the host machine is not configured properly for RAS. If this is the case, verify that the machines are set up for the correct COM port and baud rate, and make sure there are no IRQ conflicts.

  • If the machines are connected with null modem cables, verify that there is no conversion device, such as a 9-to-25-pin adapter, in use. Also verify that the null modem cable is configured correctly. Windows NT does not use the standard null modem cable specification. If the cable is configured properly and RAS still does not work properly, try replacing the null modem cable.

    If RAS is installed, you can see the correct specification for a Windows NT RAS null modem cable:

    1. From the Remote Access Service group, open Remote Access.
    2. Select Help from the menu bar.
    3. Select Cabling Requirements from the Reference section at the bottom of the list.
    4. Select Null Modem Cabling under the See Also section.

    The screen that appears will explain the specifications for either a 9- or 25-pin null modem cable.

  • There could be a problem with the physical port of the machine. Make sure that the port works properly with other telecommunication packages, such as Terminal, or try using another COM port.

  • There could be a hardware problem with the modem in the machine. Make sure that the modem works properly with other telecommunication packages, such as Terminal, or try using another modem.

  • RAS may not be started on the host Windows NT machine. On the host machine, open the Remote Access Admin Icon in the Remote Access Service group. Select the Server menu and verify that RAS has been started (that is, Start Remote Access Service will be dimmed if it has been started).

Additional reference words: 3.10 KBCategory: KBSubcategory: ntrmt