Assume that you try to establish a dial-up connection by using an Integrated Services Digital Network (ISDN) device in Windows 8 or in Windows Server 2012. However, the ISDN device does not connect to the network, and you receive the following error message:
Error 651: The Modem (or other connecting device) has reported an error.
This issue occurs because the ISDN device driver does not initialize successfully.
To resolve this issue, uninstall the device driver, and then use Windows Update to obtain the latest driver that is recommended for the ISDN device.
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows
To work around this issue, follow these steps:
Press the Windows logo Key+R to open the Run box.
Type regedit in the Run box, and then press Enter.
Locate and then select the following registry subkey: