FIX: A program cannot re-establish communication with a modem device after the USB cable is quickly reconnected

After you disconnect and quickly reconnect a universal serial bus (USB) cable, a program cannot re-establish communication with the USB modem device. This behavior describes the typical symptoms. The exact symptoms that you experience depend on the program that you are using.

This problem occurs because of an issue with the Unimdm.tsp file.

Microsoft Windows XP

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.


The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

Microsoft Windows 2000

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.


The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

To work around this problem, quit the program, disconnect the USB cable from the modem device for 10 seconds, and then reconnect the USB cable to the modem device. You can expect the program to re-establish communication with the modem device.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

Steps to reproduce the behavior

To reproduce the behavior, use any modem class driver and a program that uses Telephony Application Programming Interface (TAPI). For example, if you use a dial-up network or if you use remote access, follow these steps:

1. Click Start, click My Computer, click My Network Places, and then click View network connections.
2. Click Create a new connection, and then follow the prompts in the New Connection Wizard. Click Next on each page of the wizard.
3. Click Connect to the network at my workplace. By default, Dial-up connection is selected.
4. Type Temp in the Company Name box.
5. Enter a phone number for the system to dial.
6. Make the connection available for anyone's use.
7. After you finish the wizard, dial the Temp connection.
8. While the system is connecting, disconnect and reconnect the USB cable within three seconds. You receive the following error message:
   Error 651: The modem (or other connecting device) has reported an error.
9. Cancel the Temp connection, and then double-click the Temp connection.
10. Dial the Temp connection. You receive the following error message:
    Error 633: The modem (or other connecting device) is already in use or is not configured properly.
    You can repeatedly cancel and dial the Temp connection.

After you install the update that is mentioned in the "Resolution" section, the program might take 10 seconds to re-establish a connection to the USB modem device.