Plantronics Voyager Legend UC - Manual (Page 14)

Battery Level Tone Voice Prompt
30 minutes of talk time
remaining (this alert only occurs
during an active call) Double high tone every 15
minutes "Battery Low" repeats every 30
minutes
10 minutes of talk time
remaining Triple high tone every 30
seconds "Recharge Headset" every 3
minutes
Low Battery Warnings
14