Plantronics CS500 series beeps and tones

Out of Range - 2 beeps (one “mid” tone when back in range)

Low Battery -1 beep every 10 sec (Recharge headset for 1-3 hours or until charge light goes solid)

Mute - 3 rapid beeps every 15 seconds when engaged

Incoming call - 3 short beeps for each ring (only if you have an HL10 handset lifter)