Picture of Adapting a Telephone Handset to a Cell Phone
By Bill Reeve (
Adapted for instructables by Mouse (

Disclaimer: The procedure described here may not work for you - that's a risk you have to take. If it doesn't work, or if you break something, it's not my fault - it's part of the adventure's risk. I assume you know how to solder. If you don't, please learn before attempting this procedure.

Introduction: Hooking up an old telephone handset to work with a cell phone is simply a matter of connecting together the correct wires. The goal is to substitute the microphone and speaker in the old telephone's handset for the microphone and speaker in the cell phone's handsfree headset. We will do this by attaching the handsfree headset plug (the metal end that plugs into the cell phone) to the end of the coiled cord attached the old handset. The trick is to identify, and connect together, the correct wires.
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Step 1: Materials

Picture of Materials
You will need:

1. the handset from an old, broken and late-model telephone (please don't destroy an antique rotary phone),

2. the coiled telephone cord that connected the handset to the body of the old phone, and

3. a wired handsfree headset that works with your cell phone.

You will also need a soldering iron and some shrink sleeving.

If your handsfree headset is significantly different from the one used in this example, you might need a method of measuring electrical continuity, like a digital volt meter (DVM) that can measure electrical resistance. If you don't own, or can't borrow and DVM, you can still make this work with a different headset, but you will need to identify the matching wires by inspection or trial-and error.
msimonaƶƶi4 months ago
I made it with an old Italian handset and an LG stereo handset.
I used the original wire (only 3 wires inside), so I identified and use the mic, left (or right) and ground removing and not using one of the speaker.
My suggestion is: in the lg handset there are 5 wires Ground, Speaker, Mic, Other speaker and another Ground. with the multimeter check the speaker that you want to use and remove the other one. The important thing is make a link and sold together the 2 grounds.
slappy262 years ago
This is great instructables, I'm attempting to do the same thing but i'd like not to rip off one working handsfree headset, so i'm looking for the 3.5" jack for now with no luck at all. So my question is: because the old fashioned headset is not stereo (is it?!) can i use a 3 pole jack excluding one of the two line out and make it mono instead of stereo?
jahedq3 years ago
I am interested in a characteristic of older (102 to 500 series) ATT and Western Electric phones, namely that when you talk on those phones, you can hear your own voice. I am convinced that the lack of this characteristic contributes to the annoying occurance of people raising their voices and shouting into their cell phones. (If you could hear your own voice, no one would shout into the mouthpiece, since you would be shouting into your own ear!)

This is annoying in restaurants, and in my living room. The quality of the conversation is definately enhanced by this feedback, and also by the better audio quality of the analog technology of older phones. I thought I might be remembering better than it was, so I bought an old ATT princess phone to see if it sounded as good as I remembered it.

It does!

I was very excited to find there are a few "retro" handsets on the market for cell phones. I bought one, but the sound quality is digital, and there is no feedback to the earpiece.

I was excited again to see that the connecting cord to the handset had the old fashioned modular connector on it, and that it would fit into the ATT handset! So I tried, but no luck. No audio feedback.

Here's my question: How does the Western Electric 500 series, for example, provide the audio feedback from the mouthpiece to the earpiece? Is the circuitry in the cradle portion of the phone? Can the circuitry or components be isolated so that one could create an adapter that would allow you to plug a cell phone into a 500 series handset, or even the base, and get the audio feedback to the earpiece?


Hope you can read this OK.
I have that similar feature (voice feedback) in my old mobile phone. its called private talk. i can turn it on & off. maybe similar circuit can be used.
Very interesting! What is the model and maker and year of your old mobile phone?

This is the phone :

Samsung CDMA Explore SCH5259

Also I made a mistake. The name of that feature is not Private talk, It's whisper talk.

Hope this helps.
Nebulosa jahedq3 years ago
In those old phones there was a rather complex audio transformer inside the base that provided the feedback into the earpiece. The same could be accomplished with some electronics.
jahedq Nebulosa3 years ago
There is a Wikipedia article on "sidetone" which appears to be the sound I am talking about. I still don't get completely. WP says all phones (to this day) are designed with consideration for sidetone, some to eliminate it, some to put in a measured amount. All I can say is that the old WE phones, from the 30's to the princess phones and a few beyond, had a lot of it, and I liked it.
1) it was analog, and apparently, like LP records, had a more true reproduction of our voice, and
2) the audio feedback prevented the speaker from yelling, because you would be yelling into your ear.

Every time I am annoyed by a loud cell user in a restaurant, I wish I had a different phone to hand them. Or a handset you could plug into the cell port to get the annoyer to pipe down.

Do you understand the circuitry and could you build such a handset?

anallie03 years ago
Warning! Always use a headset original, because I discovered that the jack connections are different in different phones
jwahid3 years ago
nice, I feel so regret i throw away my grand ma phone
sonicgear3 years ago
I think you should provide more picture for this. More easy for me to understand. can't you ?
beachflight4 years ago
I wanted to do this project for a while after seeing this, but couldn't find a good handset until I came upon this gem in Goodwill. For some reason it has a strong echo effect. Any thoughts, electrical wizards? Anyways, planned improvements are replacement wood for the mouthpiece and a cord with a switch for better functionality. Thanks for the great instructable hereaftermouse!
Bosun Rick4 years ago
I don't know if there's an insrtuctable posted for this, or not; But why not take the innards out of a cell phone, and put them into a regular sized cordless phone? This would make finding the darn thing a lot easier, and maybe the batteries would stay charged up longer too!
It would require a bit more soldering, and probably a giant sized magnifying glass, a case of Rum or Burbon, and 6 months, but it would be cool!
Frmeyers4 years ago
Thanks! Really clear ible instructions. I have been looking for a handset for a friend who is blind and has trouble with how close to hold my iPhone when on speaker. This is exactly what I needed.
RetroTechno5 years ago
If you want to try a more sturdy connection, you can find the bare 4-conductor 3.5mm plugs online from several sources like this one pretty cheap:
volksyeger5 years ago
I AM SO DOING THIS ONE!!! i just need to gather the supplies. and finnaly a girl that is smart, AND cute!
 whoa...your right. :) I made this and my friends just cracked up for like an hour
 whoa...your right. :) I made this and my friends just cracked up for like an hour
Swampy5 years ago
Nice instructable. One that I've botched together a few times but always been too lazy to document :o)

I'm right in thinking this is Captain Mouse of the HMS Chronabelle fame aren't I?

mouse.reeve (author)  Swampy5 years ago
 The very same.
neotom6665 years ago
omg your beautiful
mbainrot5 years ago
awesome instructable, such a shame my phone doesn't have a 2.5/3.5mm stereo plug,

+agree with shadowfoxxxx :)
haha that's cool. Totally gonna try this.
Also, you're cute.
jdkmetal5 years ago
Good one! I'm guessing that you have a blackberry or something similar? I have 2 or 3 of those headset laying around.....
Love it!
really well broken down, and easy to follow.......a true credit to instructables
Nice write up, Mouse. Maybe I'll get around to this soon.