Phone Line ===> US Robotics ===> Brother Fax
Configure Brother Fax  - No to easy receive - answer on ring 4
Configure US Robotics Software - in my case MS Fax on Server 2003 to answer on ring 1

From: http://www.westernet.net/Help/RJ45.htm

• Pair 1
  • White with Blue
    • Tip
  • Blue
    • Ring

From: http://en.wikipedia.org/wiki/Tip_and_ring

  Tip has a potential of 0 volts with respect to ground, while the battery side carries a DC potential of −48V
  when in the on-hook (idle) state (nominally −50 volts in the UK).

From: http://wiki.answers.com/Q/What_is_Phone_line_polarity

  The red wire is the "ring" or negative wire. The green wire is the "tip" or positive wire.
  

From: http://en.wikipedia.org/wiki/Tip_and_ring#Polarity

  tip wire coded green and ring coded red.    
  

From: http://www.lanshack.com/wire_phone_jack.aspx

Nice Diagram

From: http://www.eeweb.com/blog/extreme_circuits/phone-line-polarity-checker

  
  Because modern phones rectify the DC voltage from the telephone lines before regulating it and 
  because the ring and voice signals are AC, for voice communications the polarity doesn’t really matter.

http://helpdesk.princeton.edu/kb/display.plx?ID=1019

 Exchange ActiveSync

http://voipsetup.100webspace.net/ipphone.php?afiles=updatePolycomFirmware.php