... telephone 1.Numbers record 2. Flash ,mute,redial 3.Ringer HI/Low 4.lock,Ring music ,calculator Hot line headset handset phone,call center ... the backlight lamp flashes for indication at ringing of incoming call Headset volume adjustment: 2-step toggling adjustment and 2-step soft ... headphone It can be used without external power source The telephone has white and black colors to choose 0.3% spare ...