Then insert each page into the documents at the cursor. Or alternately, you can use the clipboard to copy each scanned image from a image program to Paste into the word processor. The word processor allows you to add additional associated text to the document of course. Word processors each have their own quirks, but the Word print driver should automatically add page breaks as needed to prevent if possible any image from being continued across a page border, that is, the scanned pages should arrive as whole fax pages. Always check the Print Preview to be sure it is as expected.
Most modems come with free fax software, and more fully featured fax software can be purchased.
Most such fax software will support multiple pages. Fax software will allow you to include multiple pages from disk files. You can scan multiple page fax directly from WinFax, or you can open previous scans from files. I use WinFax Pro 8.0, and it's very strong, for example, it runs two fax modems simultaneously on two phone lines, and can be configured in various ways, sending two fax at once, or one line for sending and one line for receiving. Winfax Pro is very fully featured.