Introduction:
     *  Specially designed and user friendly button.
     *  Electronic sound volume control suitable for noisy environment.
     *  Speak and listen volume control.　　　　　　
     *  Manual/Auto answering
     *  Different ringtone for external and internal call
     *  Recording interface for connecting to any voice recording system
     *  Flexible transfer depending on the telephone switch timing, choose between 100ms/300ms
     *  Headset stands to prolong lifespan of the headphone.