The FaxSTF software automatically defaults to selecting the Printer/Modem port for the Modem, which in turn occupies that port causing the error, and may disrupt the operation of any AppleTalk device connected to the printer/modem port.
To resolve the issue, perform the following steps:
1. Open the Fax Browser within the FaxSTF folder.
2. Select Settings from the Edit menu.
3. Choose Port from the icons on the left-side of the Settings window.
4. Choose Internal Modem, instead of Printer-Modem Port.
5. Restart the computer.
Note: Macintosh PowerBook G3 Series computers should not be confused with Macintosh PowerBook G3 computers. Though the names are similar, there are significant differences. To visually identify which type of computer you have, close the display and inspect the display case. A Macintosh PowerBook G3 has a small, six-color Apple logo on the display case. A Macintosh PowerBook G3 Series computer has a large Apple logo on the display case that is not six-colored.