Hello,

Recently, I tried to plug headsets on my n900, but it didn't work.
There was a constant humming in the headphone (those kind of noise which means "Unplug me quicklyyyy !!! ").

I read somewhere the n900 jack follow the OMTP norme, and I've got a OMTP "stereo headphone + microphone" adapter.
I've got a CTIA <-> OMTP adapter too.

If I only plug the headphone on the phone, it works well (but I don't have a microphone)
If I plug the headphone+microphone using the OMTP adapter, it hums loudly and it's unusable.
If I plug the headphone+microphone using the OMTP adapter + CTIA<->OMTP adapter, it hums loudly and it's unusable too.
If I plug the headset sold with the phone, it works.

How does the n900 jack work ?
Is there a way to plug any headset on it ?