I tried mightily to get an adapter that could work with everything, and not be clobbered by the EMI from the nearby cell tower. Everything commercial I could find failed. I talked to some of the companies that make them and they thought "it cannot be done" (mostly about the EMI stuff) haha, i guess cannot be done if you don't know how.
I decided to make it 60's military utilitarian to be extra awesome:
This is for Helicopter headsets (low impedance) David Clark H10-76
It works with my cell and my computer, AND my IP phone!
As super quick Express PCB board and all!
It works without interference at more than 20V/M!
It also has a "sidetone" which for some reason no one has. This makes it so you can hear yourself when you talk. Which is SUPEr necessary IMo.