For a std one line configuration you only need the Red and White. White is ring, Red is tip. If you have a keyed-PBX system with multiple lines and phones, you still only need to use red white from the phone to the PBX. they Keyer takes care of all the other messy junk. If you have a simple two line phone and two line service then use the black and yellow. yellow being ring black being tip.
I just finisheda 166Hr live switch over at the states largest gold mine. Took out there OLD system and installed a brand new high tech fancy phone system. I wired 258 phones in one building, 60 in another, 98 in another and 122 in yet another.