Use PC Headset (2x 3,5mm Jack) with Nokie E51 / E90 (4-pole 2,5mm Jack)

[biginbiz]

Hi,

i want to use a standard PC Headset for Nokia E51 or E90. This SmartPhone needs a 4-pole 2,5mm Jack.

My Intention is to create a Adapter Box with an answer button:

Nokia E51 2,5mm 4 pole Headset jack > Adapter Box > Standard PC Headset with 2x 3,5mm Jacks (Mic + Headphones=

The Pinout of this (Nokia calls it "AV-Connector") can be found here: http://www.forum.nokia.com/main/resources/technologies/connectivity/av_connector.html

Additionally Nokia says that their headsets comply to the OMTP "Wired Analog Audio" specification.
You can find the spec here:
http://www.omtp.org/Publications/Display.aspx?Id=e8dc6c67-9b36-4bf5-b532-05c7742ac36b#

The section LC0080 shows a pinout of such an Headset.

I bought an 2,5mm (4-pole) to 3,5mm (4-pole) Adapter "Nokia AD-52" and tested a standard PC Headphones - they are recognized by the SmartPhone and work - so they must be physically compatible.

The sound output of my adapter is clear. But i wonder how to wire the standard PC Headset Microphone jack (3,5mm) because the Microphone 3,5mm Jack has 3 Pins...

Thx in advance.

[biginbiz]

I found this one:

http://www.x50v.it/content/view/1159/69/

The initial pinout auf the Axim is the same despite the fact of being 3,5mm than 2,5mm.
In this wiring scheme, they connected the MIC-IN Pin with both the tip and the first ring of the 3,5mm stereo line socket.

Would this also work for my Nokia ?