Fax Line with US Robotics Modem

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

What is the Easy Receive setting?

From: http://welcome.solutions.brother.com/BSC/public/eu/gb/en/faq/faq/000000/002400/000060/faq002460_000.html?reg=eu&c=gb&lang=en&prod=mfc9440cn_all

  OFF means you will have to activate the Brother machine yourself by lifting the handset of an extension telephone on the same line 
  as your Brother machine, then doing one of the following:
      If you are at the Brother machine, press the Mono Start or Colour Start key.
      If you are not at the Brother machine, press *51

carrying LAN and telephony on the same cables

From: http://www.zytrax.com/tech/layer_1/cables/mixed.html

We get a lot of mail about carrying LAN and telephony on the same cables. This page is designed to give you 
some information to let YOU decide whether you want to do this or not. It is not easy and you should be very
comfortable with all the information here before you set out to destroy your premises wiring!

Pin No. 	strand color 	Name
1 	white and orange 	LAN (TX_D1+)
2 	orange 			LAN (TX_D1-)
3 	white and green 	LAN (RX_D2+)
4 	blue 			Telephone 1
5 	white and blue 		Telephone 1
6 	green 			LAN (RX_D2-)
7 	white and brown 	Telephone 2
8 	brown 			Telephone 2

Telephone Line Parity

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.