I work in a call center type environment, where we use Cisco IP phones and plantronics wired headsets to dispatch out technicians to a job site. For the sake of keeping appearances more professional, it is frowned upon to listen to wear earbuds to listen to music. But I like most Americans do not do well in quiet situations around other people. Also talking to your cube neighbor gets old fast in an 8+ hour shift 5 days a week.

My solution is to feed music from my computer or other device through the headset that I am already wearing. I searched for an adapter for this purpose, but since I didn't find one, I must take matters into my own hands.

Step 1: Collect Supplies and Tools.

Tools:

Voltmeter
electrical tape
sharpie
soldering pen and solder
exact o knife
plastic cement
philips screwdriver
hot glue gun
wire stripper
(not shown) and dremel with bits

Supplies:

small project box
car stereo cable (1/8" jack)
plantronics headset cord extension
small toggle switch

It is important to note that while the extension cord looks similar to a standard phone jack, the cord end needed for the cisco phone and plantronics headsets are unique and a standard phone cord extension will not work. I happened to have this cord handy, but if you need to find them they sell on amazon for about $12. You may be able to find one cheaper if you look hard enough. All that being said the the other supplies set me back about $13 total. You can probably get those cheaper too, If you look online. I also chose all black cords so as not to raise suspicion.

Step 2: Wiring Thoughts and Plans

First I had to identify the wires that went to my ear piece.

The first pic is of the cord that adapts the cisco phone plug to my plantronics headset. Using the voltmeter I found out which color went to which lead on the plantronics end. I also identified which plantronics leads went to the ear piece.

Green and Red are the important ones in the mix.

The last pic here is my poor excuse for a wiring diagram.

I decided the best way to do things would be to hook the red and green wires from our extension cord to the center point on the toggle. And add the audio input to one side. The switch is not absolutely necessary, but it is a feature that I wanted in case other people sit at my desk. What I am setting up is not 'against the rules', it is however frowned upon so I do not want to advertise that I have this device to all of my lovely coworkers if I can avoid it.

Step 3: Prep Cords

First cord to prep was the audio cable. When I stripped it I found three wires. This is normal since it is a stereo cable. The blue and green wires are for each channel, with the red as a common between the two. I ran the two channels together so that I could get the stereo feed through the one ear piece in my headset. I found out that this particular audio cable has a laminate coating on the wires for insulation and that is where the color comes from. you can burn this off with a lighter. That's what I had to do.

Then comes the plantronics extension cable. I cut out the scrunched up bit because I did not need the length and I don't want to mess with squirrely wires. eventually I took all of the black insulation off of the female end to make the wires more flexible.

Step 4: Test Wiring

I hooked up the female side of the extension and the audio cable to the switch just to test the basics. But this is one of many dry runs that I did along the way testing with actual audio and the voltmeter. The only way to make sure your project does not end in disappointment is to test and test often at every stage of every step.

Step 5: Box Customization

I laid out all of the bits on the project box and found the configuration that I liked. Then went to town with my dremel making everything just right.

Step 6: Soldering and Finishing

The soldering was easy especially when you use flux (a must for small wiring). Heat shrink tubing would have made this look really nice but all I had was some electrical tape. You can also see where I used the hot glue and cement to secure things inside the project box.

Step 7: Enjoy.

Here is the final product. Not the prettiest thing in the world, but it is simple, does the job, and doesn't draw too much attention to me... unless I start dancing in my cubical that is. :)