I use two kinds of microhpones (4 pin) :
=========== Wired =========
This mic actually has only 2 working wires (3rd an 4th rings connected to MIC board). Top 1st and 2nd rings are just empty.
=========== Wireless =========
==== Problem ===
I can use WIRED mic perfectly with LG, but not with MOTOROLA (MOTOROLA cant see that as "mic", thus doesnt get any voice from it).
However, I tried to use Wireless microphone system with LG, it cant obtain voice (i have tried all ways), but MOTOROLA works with appliance perfectly.
As you know, the receiver outputs audio exactly on the same 3rd and 4th rings, but in addition, it adds some electrical power too, as a person is able to hear it softly in speakers (as opposed to WIRED microphone, which doesnt output anythig if something doesnt powers it)
Addition: I am a bit technician and tried to manually cut wires & connect lines with each other, to every possible combination, but in none of the case the LG worked with the applicance...
p.s. I dont think that it matters whether 3rd or in 4th ring is "ground", because when I have exchanged 3rd and 4rd (ground & microphone) wires, it didnt matter for phones. They are working the same way, only with "beloved" types...