Lone worker will make an emergency call if he user fails to respond at regular intervals.
It is a simple countdown timer built into the radio. When the time period reaches zero the radio bleeps to prompt the user to acknowledge they are OK by pressing a button. The button-press cancels the bleeping and resets the countdown timer which again starts counting down.
Lone worker can normally be enabled and disabled as and when required.
Only certain models of radio have Lone Worker capabilities.