MightyFax is software that communicates with your faxmodem to send and receive faxes. You can fax directly from Windows software, including Microsoft Word or any other Windows software, directly to MightyFax. You do this by printing to the MightyFax printer, which creates a fax file out of your print job, and passes it to MightyFax for transmission as a fax.
MightyFax works directly with the modem. It does not use your Internet connection, if you use a dial-up Internet service. Just as you cannot use a fax machine while also using the Internet on the same telephone line, you cannot use MightyFax and your Internet connection at the same time.