Thanks for the responses. I figured that the mono/stereo issue may be the problem, and so went out and bought a mono adapter. Unfortunately, the phone behaves the same way, reporting that the headset is disconnected if it is pushed in all the way. Bit of a shame. Love the phone otherwise but this is becoming a bit of a deal breaker for home-office use

I am trying to figure out how to connect the Beocom 3 to a headset using the 3.5mm jack. When I use 3.5mm jacks, mono or stereo, it does not work and the phone reports that no headset is connected. If I pull the plug about half way out of the jack, the phone reports that a headset is connected and I get sound in the headset, but the microphone can only