adapter cable from smartphone to both headset and car stereo aux input

[taxciter]

I am looking to connect my smartphone's 3.5mm TRRS phone jack to both 1. the phone manufacturer's 3.5mm TRRS headset (preserving functionality of mic and all control buttons) and 2. a 3.5mm TRS aux car audio input. I do not want to lose the full functionality of the headset while sending audio to the car stereo.
There would be have to be continuity between TRRS contacts since the phone must read manufacturer-specific resistances when headset buttons are pressed. The TRS contacts may or may not need to be transformer isolated, I don't know yet.
I can't find such an adapter pre-made, and I don't want to make it myself unless I have to.
In this case I do not want a bluetooth or wireless solution. It must be hard-wired.
Thanks for your attention and comments!

 

[Skeefers]

Is this what you're looking for?

http/www.amazon.com/Ledhill-3-5-mm-Stereo-Plus-Mic-Conductor-Splitter/dp/B00BJZJNIK

 

[taxciter]

Is this what you're looking for?

http/www.amazon.com/Ledhill-3-5-mm-Stereo-Plus-Mic-Conductor-Splitter/dp/B00BJZJNIK

Thanks, Skeefers, but:" it does not support the volume, pause, stop or skip control from the iPhone/iPad/iPod's headphones remote control buttons"

 

[Skeefers]

Ok, but other than that it's what you need, correct? I'll keep looking for one that supports the other controls.

 

[taxciter]

Ok, but other than that it's what you need, correct? I'll keep looking for one that supports the other controls.

Here is a quick drawing of how I imagine it schematically:

 

[Skeefers]

Well, I think this is going to be as close as you're going to get to what you're looking for, but I'm not sure if it will pass the controls through or not as they don't specify on the page or in the video.

http/www.esdevices.com/products/wiretap

Since the one female connector says it's TRRS, I'm thinking it has a good chance of working, but I'm not 100% certain. There's contact info for the company on the site, so hopefully they'd be able to answer that for you. The second female connector, being only TRS, would be perfect for connecting to your car's stereo, though.

 

[taxciter]

Well, I think this is going to be as close as you're going to get to what you're looking for, but I'm not sure if it will pass the controls through or not as they don't specify on the page or in the video.

http/www.esdevices.com/products/wiretap

Since the one female connector says it's TRRS, I'm thinking it has a good chance of working, but I'm not 100% certain. There's contact info for the company on the site, so hopefully they'd be able to answer that for you. The second female connector, being only TRS, would be perfect for connecting to your car's stereo, though.

I have asked the company to confirm and will post again after I get word. I bet this will be it.

 

[Skeefers]

I've got my fingers crossed for ya...

 

[taxciter]

I've got my fingers crossed for ya...

Thanks, Skeefers.
The Extrasensory Devices Wiretap will meet my goal. Here's the confirmation from ESDevices:
"Hi, Henry-- No need to build anything from scratch: yes, all of the standard headset controls work as expected with the wiretap. The device is designed specifically to pass all signals from/to the headset. Thanks, Jarrod Whaley"

 

[Skeefers]

Awesome! Glad to hear it