Your phone will automatically know to use the headset when plugged in. Most mobile/cordless/ corded phones will have a 2.5mm headset jack on the side or top of the phone to quickly and easily plug a headset into.
Headset is not ear specific and you can easily switch the headset to fit either ear. Binaural (both ears covered) headsets can be worn with the microphone being positioned on either ear.
For best results, always position your microphone approximately 1/4 of an inch away from the edge of your mouth. A Noise-Canceling microphone makes your voice clearer to your caller and cuts down background noise.
For traffic safety, never use the headset while riding a bicycle, motor bike, or while driving a car.