US Robotics 56K Series Manual page 35

After you have made these changes, reinstall your modem following the directions in
12.
the "Installing the modem with Windows 95, Windows 98, and Windows NT"
chapter. Once your modem is properly installed, make sure you have the correct
COM port and IRQ settings in your software and/or in the Windows Device
Manager.
POSSIBLE SOLUTION
You may not be entering modem commands in the proper manner. Type in all upper case
(AT) or all lower case (at).
POSSIBLE SOLUTION
You may not be using fully Windows-based communications software. The modem
requires fully Windows based software. Some Windows-based communications and
Internet software use a DOS-based dialer. Check with the software company.
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