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Testing a Modem

In addition to providing controls that enable you to configure the modem and its COM port, Windows 98 enables you to perform troubleshooting on the modem. If you click on the Diagnostics tab on the Modems Properties sheet, the Diagnostics page appears.

To test a modem, select the modem from the list by clicking on its assigned port; then choose More Info. Windows 98 attempts to communicate with the modem, and if successful, displays a More Info dialog box. The More Info dialog box contains information about the COM port and modem, including the interrupt, I/O base address, UART type, and recommended maximum speed, as well as modem commands the diagnostic utility sends to the modem and the responses it receives.

Some responses in the More Info dialog box might read ERROR, which does not necessarily indicate a modem error. The modem might not support the related command. If the diagnostic utility reports more than a few ERROR states, however, you probably have a problem with the modem or are using the wrong driver for the modem.


If Windows 98 can't communicate with the modem, an error message appears, followed by a More Info dialog box that reports the COM port information (interrupt, base address, and UART) but no other information.

The modem diagnostic utility is a 16-bit application, which means that it can't test the port if you're using the port. If Microsoft Fax is monitoring the port for incoming calls, for example, you must set the answer mode to Don't Answer, making the port available to the diagnostic utility. And because the diagnostic utility is a 16-bit application, it can't test for parallel-port modems.


At this point, you should have your COM ports and modem(s) configured and working properly.