KB146639 - Using Zoom Comstar Plug and Play Modems with Windows

Article ID: 146639

Article Last Modified on 1/19/2007

Microsoft Windows 95
Microsoft Windows 98 Standard Edition

This article was previously published under Q146639

If this article does not describe your hardware-related issue, please see the following Microsoft Web site to view more articles about hardware:

http://support.microsoft.com/default.aspx/w98?sid=460

SYMPTOMS

When you attempt to install a Zoom Comstar 14.4 or 28.8 Plug and Play modem in Windows, you may experience one or more of the following problems:

If the COM1 and COM2 ports are already installed and listed in Device Manager when you install the modem, the modem may be configured to use the COM5 port. This problem is known to occur even when the COM3 and COM4 ports are not already installed and listed in Device Manager.
After you install the modem, the serial port that the modem is configured to use is not listed in Device Manager. To determine which serial port the modem is configured to use, click the modem in Device Manager, and then click Properties.
You may be unable to communicate with the modem using the ECHO command from a command prompt in Windows unless the real-mode drivers that came with the modem are installed in the Autoexec.bat and Config.sys files.
You may be unable to establish a connection using the modem with HyperTerminal, Dial-Up Networking, Phone Dialer, or any other 32-bit communications program.

CAUSE

These problems are known to occur with the Zoom Comstar 14.4 and 28.8 Plug and Play modems when they are used with Windows. These problems are not caused by a problem in Windows.

RESOLUTION

For information about resolving these problems, please contact Zoom Telephonics.

MORE INFORMATION

When you install a Zoom Comstar 14.4 or 28.8 Plug and Play modem in Windows, the modem is not configured to use the COM3 or COM4 ports even if those ports are not already installed and listed in Device Manager. The modem may still function correctly with 32-bit communications programs when configured to use the COM5 port, but it may not function correctly with 16-bit communications programs.

After you have successfully installed the modem, you may be unable to communicate with the modem using the ECHO command unless the real-mode drivers that came with the modem are installed. When you use real-mode drivers for your modem in Windows, you are unable to take full advantage of the 32-bit communications architecture that is available. For this reason, using real-mode modem drivers in Windows is not recommended.

You may also be unable to establish a connection using the modem with 32- bit communications programs. This problem occurs when the initialization strings for the Zoom Comstar modem in the registry are incorrect. For example, one of the initialization strings for the modem should be:

AT&FE0V0&C1&D2S95=47S0=0<cr>

In some cases, the initialization string that is actually placed in the registry is:

AT&FE0V0&C1&D2S95<cr>

When the initialization strings are truncated in this manner and you attempt to establish a connection using a 32-bit communications program, the Modemlog.txt file may indicate that the correct strings were sent to the modem.

Zoom Telephonics has a resolution for the initialization string truncation problem. Please contact Zoom to obtain an updated driver (version 1.2.4, dated 12/22/95).

Keywords: kbenv kbhardware kbprb KB146639