Headset Buddy: PC Computer Headset to Phone Adapter - Dual 3.5mm to 2.5mm (01-PC35-PH25) Use headset on computer and home or office phone that has a 2.5mm headset jack Convert two 3.5mm plugs to single 2.5mm plug. For use on standard 2.5mm phone headset jacks Reduce clutter with single headset. Great for traveling, carry just one headset Works with mono and stereo headsets