I have office phones that are connected to 4 lines. I want to add a cord-cordless 2 line phone. When I connect the new 2 line phone to the old jacks, I get no dial tone. Opening the jack I found 8 wires. Which colors do I connect to the standard 2 line jack of red/green and yellow/black? The 8 color wires are white-blue, blue, purple, red-white, orange, orange-white, green and white-green. I tried various combinations with no success. Thank you.