Copy this Universal INF file onto a blank 3.5-inch disk. When prompted for the driver during the installation, select Have Disk and direct the installation to the 3.5-inch drive. Select mdmusr01.inf from the 3.5-inch disk and follow the prompts to finish the installation.
Save his file to a blank 3.5-inch disk. In Control Panel, double-click Modems and remove all USRobotics modems. Restart your computer. When prompted, select Change or Have Disk and point the installation to the 3.5-inch disk. Select the appropriate model and follow the prompts to finish the installation.