The SBS 2011 Fax printer 32-bit drivers currently shipped with SBS 2011 are not compatible with Windows XP. They only work with Vista and newer. Attempting to send a fax on an XP machine with these settings does nothing and no error messages are displayed.

To solve, you can use the driver from SBS 2003 SP2, as these are compatible with the SBS 2011 Fax system. They can be found inside the Windows 2003 SP2 download (see below for detailed instructions), or directly from an SBS 2003 (located in c:\windows\system32\spool\drivers\w32x86\3. The files you need are these:

FXSAPI.DLL

FXSDRV.DLL

FXSRES.DLL

FXSTIFF.DLL

FXSUI.DLL

FXSWZRD.DLL

Most people won't have an SBS 2003 with SP2 anymore.   ...