The base unit can detect a button press within a 600 ft range from the base device. Help can still be sent if you aren’t able to communicate with the monitoring center and you are within 600 ft of the base device.
It is recommended to test your base device, as well as any/all buttons, monthly to ensure they are working properly. Simply press the button and when you’re connected to the monitoring center, state that you are testing your device/button and no help is needed.