1. Find the white wire going from the switch to terminal ‘F’ on the network. Remove this wire from the network and attach it to the terminal on the polarity guard that corresponds with the green wire.
2. Attach the green wire from the polarity guard to terminal ‘F’ on the network.
3. Find the blue wire going from the switch to terminal ‘C’ on the network. Remove this wire from the network and attach it to the terminal on the polarity guard that corresponds with the white wire.
4. Attach the white wire from the polarity guard to terminal ‘C’ on the network.
5. Use two-sided tape to fasten the polarity guard in place, or use the notch in the board under a screw to hold it securely. If you don’t have a convenient place to attach the guard, wrap it in electrical tape to prevent shorting, and wedge it in somewhere out of the way.

Original Western Electric polarity guard

1. Find the white wire going from the switch to terminal ‘F’ on the network. Remove this wire from the network and attach it to the terminal on the polarity guard that corresponds with the green wire (closest to the hinged cover).
2. Attach the green wire from the polarity guard to terminal ‘F’ on the network.
3. Find the blue wire going from the switch to terminal ‘C’ on the network. Remove this wire from the network and attach it to the terminal on the polarity guard that corresponds with the white wire (furthest from hinged cover).
4. Attach the white wire from the polarity guard to terminal ‘C’ on the network.
5. Tuck the unit somewhere out of the way. In a Princess phone, the best place is on edge, right in front of the network, placed close to the keypad.