Build your own intercom or walkie talkie out of two old cordless phones

Step 6: Troubleshooting

Make sure the cable works:
Find a phone where you can hear the dial tone. Now hang up and replace the line with the cable you plan to use, check to hear a dial tone now. If not then your cable is bad.

Make sure the phones work:
Temporary replace your home phone with one of the project phones, check to hear a dial tone. Then make a call to see if the microphone and the speaker work in the handset. And to see if the handset has a charge if it applicable. If you fail to make a call for any reason the phone is bad.

Make sure the Coupler makes a circuit:
Take the battery out of the coupler. The battery must be out. Then go to a working phone and make the connections in this order

Wall jack------> to cable -------->to the Coupler-------->to another cable------->to phone

This will check if you connected the right wires in the coupler. Pick up the phone and listen you should hear nothing, if you do here a dial tone then the wrong wires are soldered, or you have short in the coupler. If you move the coupler and you hear scratching sounds then you have a bad connection, and must re solder or better insolate.

If you hear nothing that is a good sign so far, now take a screwdriver or something metal and complete the circuit at the 9v battery connector. You should hear a dial tone now. If not then your connection on the red or green is just broken somewhere and you have to find it.

The green wire is just a straight shot; you do nothing with the green. The red wire is in series with the 300 ohm resistor and a 9v battery. Make sure its set up like this. I hpe this was helpful, drink your milk and have fun.
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lesklassen6 years ago
Can you do a 4 phone system?
RTourn (author)  lesklassen6 years ago
Although I haven't tried it I'm very sure all you need is a triple phone jack.
How would you configure an intercom with a 3-way phone splitter?
Anyone have any thoughts on making this thing to ring?

mdp8721056 years ago
if you have a 9v ac to dc adapter could you not do the same thing without having to worry about the battery running out. Also does anyone know how to get the phones to ring each other using this system?
this project is very fine and works well with my old bigger size phone for my convenience i brought two new small sized phone made by china the phones are working well with exchange, but get WSSSSSSSSSS soun when connect as separate intercom. what could be wrong. advance thanks