My father being 94 and home alone has many visitors per week randomly turning up to provide services such as cleaning, medication, meals and carers. He could be anywhere in rhe house and these people are allowed to enter using their code to access the front door. The door bell button sets off the ringer in four locations. Each is set to different volumes with lights flashing but not all with vibration. This is ideal because he knows someone is entering the house and does not jump out of his skin when someone appears from no where. Volume is quiet in the bathroom but in the lounge with the tv blaring he never misses a door entry, nor does he get a fright with too much volume as above.