Specifications: This amazing adaptor converts the standard 3.5mm smartphone plug to an for Aastra RJ9, RJ10, or RJ22 handset plug, allowing you to use your favorite smartphone headset with your for Aa more→stra office phone. The adapter outputs binaural sound for stereo headsets, meaning you will hear sound out of both ears. Convert 3.5mm OMTP smartphone plug to single 4P4C RJ9/RJ10 handset/headset plug. Save money by buying a smartphone headset, or using your existing one with your office phone 39;s headset jack. This adapter will not work with for Apple EarPods and other CTIA based headsets. Works best when paired with an amplifier. For optimal use, please plug into the headset jack on your phone.…