Their is a small button on the microphone. Does anybody knows what it is used for? Take an incoming call I suspect.

It would be great to be able to use it also for other purposes like "switch to next track" when you are using the N800 as a music player.

I think that's just because they've reused their normal phone headset and just added a new minijack connector. I would be very surprised if any input through the headset connector is accepted. When using a nokia headset connector (used for phones) there are more wires, one of which, I'm sure is for this button.

Good idea though. Another idea - inspired by recent reports on this forum would be to use your (Sony-Ericsson?) phone to remote control your N800. It seems it works right out of the box like on a normal PC. Great concept - I wish Nokia built this into their phones as well

// Kny

I believe there are no "extra connectors", otherwise plain headsets would not work in this jack. I think Nokia uses a resistor inside the headset to tell the 770 whether one of the audio channels is an input (microphone) or output (second audio channel.)

The button is a answer / terminate signal for calls that momentarily shorts one of the connectors.

I'm not 100% positive of this, but I believe that is the story.

I thought it was a mute button.

it;s a standart headset , in my Nokia N95 i have 7 buttons ot headset and 4 conector jack to phone but inside in the headset is MCU , i think there is no multy IO in jack for N800 this mus be inplemnted by hardware

sorry for my bad english, REGARDS FROM BULGARIA

"The dial button in the headset answers and disconnects the call. This is implemented by connecting the microphone to the ground."
"Basic headset (headphones + microphone + optional button): 2.5-mm or 3.5-mm, 4-pole connector, left-right-mic-ground, stereo headphones and microphone; optional button that connects the microphone line to the ground (used for call answering, call termination, and voice dialing).. "
http://www.forum.nokia.com/Resources...onnector.xhtml

I've read somewhere in the forum that you can use the button to answer skype calls.

Ernia hit the main points, HW-side; the 4-pole connectors work fine with 3-pole cables, the mic input is just shorted to ground that way.

SW-side, it does work in Skype. There's been a couple of solutions rigged to use BT headset's button as some sort of media control, and I believe one of them worked with (or has been adapted to work with) the wired headset's button as well.

i think that the start for a developer to implement media control trough the 3.5 av jack (remember, i'm a newbie, have mercy ...) is this pdf
http://sw.nokia.com/id/81ba2105-f16d...on_v1_0_en.pdf
I was just trying to understand if it were possible to control media player (or mpd) trough an adapter like the nokia ad-54. i think it's really out of my reach.
if something has already been implemented i would like to know, if you can remember it. if not i will search the forum as soon i can get an ad-hoc connection with mer

Yes; the Nokia 3.5mm 4-conductor has a second ring for the mic circuit, normalled to the sleeve as the left and right (tip and first ring, I *think*) circuits are.

This is something that I am also interested in. Did you find any useful information about this?