Step 13: A few words on PoE
It sends power by placing a potential between both brown wires (-) and both blue wires (+). Since you disconnect one of these pairs using this method, PoE will simply stop working (it is not dangerous to use PoE devices, the wires are simply disconnected.)
If you desperately need to use a low-power PoE device, you may get around this by only using one wire from each pair for phone. One example of this would be the striped brown wire and the striped blue wire. Then, the solid brown wire and solid blue wire would continue to work for PoE. However, this halves the maximum current that the cable can handle and may present a fire hazard when using large power-hungry devices. I do not recommend this, but it is a possibility.