1) Could not Open Port
This error message is usually because there is a conflict with another program or resource.

Use the System Configuration Utility - MSCONFIG to troubleshoot. Go to Start-->Run  and type MSCONFIG in the Open line and click OK. On the Startup tab, look for any programs that may control the modem and uncheck the box. If the programs listed do not seem familiar clear all of the check boxes except the following check boxes:

1. ScanRegistry
2. SystemTray
3. LoadPowerProfile
4. TaskMonitor
    

 2) "Error 630" Error Message
You may receive this error message is new devices were installed and there are conflict assignments with the devices. Use the same troubleshooting techniques as "Could not Open Port".

Use the System Configuration Utility - MSCONFIG to troubleshoot. Go to Start-->Run  and type MSCONFIG in the Open line and click OK. On the Startup tab, look for any programs that may control the modem and uncheck the box. If the programs listed do not seem familiar clear all of the check boxes except the following check boxes:

1. ScanRegistry
2. SystemTray
3. LoadPowerProfile
4. TaskMonitor

3) "Error 633: The modem is not installed or configured..."
You may receive this error message if the telephone.ini file is missing or damaged.

To resolve this issue go to Start, go to Find, click Files Or Folders, in the Named box, type telephon.ini, click Find Now. Right click the file telephon.ini and rename the file to telephon.old. If the file is not found do not worry, continue on. Exit out of the Find tool. Go to Start-->Run and type tappiini.exe and press OK. This will reinstall the telephon.ini file. Restart the computer.
 

4) General Troubleshooting
Verify that the modem will pass the Diagnostics testing. To do this, go to Control Panel, double-click the Modems icon and see if the modem is listed on the General tab. Click Diagnostics, click the COM port that the modem is connected, click More Info.

NOTE: If the More Info dialog box is displayed without an error message and there is a series of AT commands and responses, the modem has passed a diagnostics test.

NOTE: If the modem does not show up in the list, the driver may not be installed properly or at all, the modem cannot be tested. Follow the steps in the "Verify Modem Information" section in this article.