Telephone Handset Adapter

I was cleaning out my pantry when I saw an old telephone that hadn't been used in a long time. Then I had the idea to relive the old days, in a way. The idea was to repurpose the handset for use with current devices, like cell phones and laptops, etc.

1. Telephone handset
2. Coiled telephone handset cord
3. 4P4C RJ9 Female Telephone Connector 4 Wires
4. Plug P3 3,5mm
5. Electrical tape
6. Lighting to P3 3,5mm adapter (Optional)

You can repurpose a headphone jack with a microphone to make this adapter, as well as the 4P4C connector from an old telephone.

The wire colors of the 4P4C connector generally follow a pattern, as shown in the diagram. P3 jacks may not have a specific color pattern, but they do have a pattern in the pin connections, where the two extremes are the left and right channels, then the microphone, and the last one is ground. Perform a continuity test to locate each wire.

After locating each of the corresponding wires, solder the wires from the 4P4C connector to the P3 jack wires as shown in the image.

Wrap electrical tape around the wire to assemble a sturdy cable.

Connect the cord cable from handset on 4p4c connector and the P3 plug to your compatible device (such as a cell phone) and test the audio input and output on handset. You can use a voice recorder app to test it. To use it with a cell phone that only has a Lightning output, you will need a Lightning to 3.5mm adapter.

Enjoy the old times!