Actiontec electronic Plug n' Play Voice/Fax Modem V.90 ISA - Manual (Page 21)

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Step 4 Windows NT will detect the modem as a “Standard Modem”. Click the
Change button.
Step 5 Insert the modem’s installation CD-ROM and click the Have Disk button.
When prompted for the path, type the drive letter of your CD-ROM drive,
followed by a colon, and a backslash, then click OK.