Retevis Dialpad Hands-free Call Center Noise Cancellation Corded Monaural Headset Telephone(Black) Comfortable to wear: compact appearance and ergonomic design, comfortable wearing experience Clear and distinguishable for speech sound Flash time is selectable among 100/300/600ms Noise Cancellation: Noise cancellation microphone increases the voice clarity and allows superior high quality sound FSK/DTMF:The dialer can ring or silent when receive incoming calls as well the phone number will be displayed