It may seem kind of strange that you would want to know how to tap your own phone line. After all, aren't phone taps meant to be used on other people? However, there is a definite advantage to having a tap on your own line, as long as you are the one doing the tapping. The best thing you can do, especially if you are fielding some pretty important or incriminating phone calls, is to record them. You can use them for bargaining, or you can use them as evidence that someone is behaving inappropriately.
It is not too hard to learn how to tap your own phone line using simple and relatively inexpensive items that can be picked up from your local electronics store. You will need one Ferrite split core assembly, 75 feet of 28 AWG magnetic coil wire (enameled), one 1/8th inch mini-lug cable (should have tinned ends), and make sure have heat shrink tubing, tie wraps, and electrical tape.
One you have all of these items, it is time to begin learning how to tap your own phone line. Open the core assembly and wind the coil around the end that does not open. There should be roughly 100 turns of coil. You should leave a six inch tail sticking out before you start winding, and then at the end, create a second six inch tail when you clip the wire.
Use fine grit sand paper on the last half inch of the coil wire to remove the enamel. You have to be careful not to break the wire. Slip the tubing over each end of the wire for insulation purposes. Then, solder the ends of the mini phone plug to the coil wire. Use tie wraps to secure the cable to the tap, and insulate solder joints with electrical tape. Slip one (and one only) of the phone conductor circuit through the split core. You can then attach the core to a tape recorder to record all conversations that you wish.
This is a very simple way that you can create your own effective phone tap quickly and inexpensively. Additionally, you have the peace of mind that comes with being able to record conversations because you know how to tap your own phone line.