What is the three wire cable for?

The main purpose of the three-wire cable is flexibility. It has tip, ring, and sleeve wires so it can be used on any of the BCM's auxiliary input jacks. And, because it is tailed at one end, it can be used to connect easily to a wired source.

The BCM 2503 wiring kit has always included a 12 ft. plug-to-plug (tip and sleeve) cable for connecting to a radio or MOH source. This works for most applications. However, for instances where a music source is located a long distance away, the plug connections aren't ideal. A tailed cable is required to make it easier to connect to extension wires or at the cross connect. Although the BCM wiring kit does include two other tailed cables, these are for tip and ring applications so they won't work for music source inputs.

To connect to a music source using the the three-wire cable, use the tip and sleeve wires (white and black). For ring, page relay, or page audio, use the tip and ring wires (white and blue).