Correcting
the reversal in the wiring to your telephone extension socket
Step 5:
Remove the wires. You may have screw terminals on your socket, or Insulation Displacement Connectors (IDC) which will require the use of an IDC tool to connect the wires. A disposable tool is available from most phone shops, or DIY stores
You can buy a low cost IDC tool from most phone shops, or DIY stores, or wherever you can buy telephone extension wiring kits.