I replaced my previous Xerox desktop MFP with a 3215 and everything works except the fax. I set it up as per the instructions but it does not get an outside line from my PBX. I have entered the appropriate Pre-fix in Centreware Web but all I hear is a fast busy that never yields a real dial tone for the fax to access. My previous machine worked fine so I know the line is fine. Can't get any incoming faxes either. Is this just a bad fax card? I have rebooted the system but no improvement.