Almost every machine sold in the last 5 years has a modem/fax modem port as part of the machine. Adagio wants to be able to communicate directly with the fax modem so that it can tell it what phone number to dial. You will only be able to use your fax machine connected to you network if it "looks like" a fax modem to your computer. If it doesn't, then purchase a small telephone jack splitter form your local electronics store and share the fax phone line with your PC.

BTW - Adagio Receivables now allows you to e-mail your statements as PDF attachments to your clients.