What are the differences between professionally monitored, locally monitored and unmonitored medical alarms?

A professionally monitored alarm calls an alarm monitoring centre that you generally pay a monthly fee to. When you press the help button, your call is answered by an operator at the alarm company.
A locally monitored alarm calls the staff at your retirement village or aged care facility. A nurse or staff member on-site answers the call.
An unmonitored emergency dialler calls a family member, friend or 000 when triggered.