Hi

Does anyone have any ideas how the mini-USB headset that comes with most many mobile phone interfaces with the phone? Is it a simple wiring, or are there some chips inside the headset?

I found the my phone (Acer F900, a Windows Mobile phone) 's USB headset volume level is too soft. I tried to use a Motorola USB headset whose connector looks exactly the same, but it did not work - the phone did not recognize the USB headset and still played audio via loudspeaker.

I also found a USB to 3.5mm converter at a local electronics shop. However, when I used this with my 3.5mm headset, the phone still did not recognize the headset:



This converter also did not work on my old Dopod phone. However, using the same Dopod phone, about a year ago, I found the following converter that could actually work (e.g. the phone recognized the headset and audio is played properly):



However, I can't find that converter anymore.

Any ideas what's the difference that makes USB headset from one phone incompatible with other phones? Also what is the difference between the 2 converters such that one works and the other doesn't?

Thanks a lot for any hint.

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