Headphone detection resistance for smartphones?

[brainwash]

I'm trying to integrate a 4 pin TRS plug with my Android smartphone and cannot get it to recognize the jack.
I thought it was based on a small microswitch inside the plug but it seems it is actually based on some resistance. On my RAZR, pin 3 (ring 2) is the common/ground connection, pin 4 is the microphone.
I've tried putting 220 ohm from any output/input to ground and tried also with 1k, shorting pins in all combinations.
Measurements on the original headphone set shows 1.5k mic-gnd, 330ohm out-gnd.

The easy way would be to buy another headphone set and tear it down but I'm sure I'm missing something and it should just work, given that in general headphones vary widely.

[brainwash]

Never mind, stupid user problem.
It IS based on physical jack detection, I was just pressing the vol-up/down keys and if no music is playing the 'ding' is played through the phone speaker.

Actually the MIC input is not getting detected properly.

[Things]

I think the mics work a bit differently in that they have a switch on the headphone cable, which you push to activate the mic (usually). You may have to look into what this switch actually does, whether it disconnects the mic or what. It may also be that the mic is provided with a small biasing voltage, so maybe the phone is looking for a tiny load on the mic pin?

[jack32]

i once tried to connect a condenser microphone to my htc desire and could not get it to work. i was sure i had the correct pinout and everything...
it could detect headsets and headphones. no chance on microphones. and no chance on faking an headset and just using the mic...

[brainwash]

Exactly my problem now. I did not have time to order a headset just to take it apart so I just used "SoundAbout" to force the mic on while headphone are plugged in.
Interestingly enough, another headset from HTC also works and it shows 20k in one direction and ~6k in the other direction. The RAZR mic connection is also asymmetric, so this might have something to do with it.
Unloaded bias voltage is about 2 volts, if anyone is interested.