These alarms might be triggered from heat detectors and smoke detectors. They may as well be activated through Manual fire alarm activation devices such as manual call points or pull stations. There are two main types of smoke alarm systems: standard and addressable. Many fires occur at night or in a room or section that no one may be in at the time. The audible alert from the fire alarm can wake individuals up who may otherwise sleep while inhaling smoke. The alert can also provide an early signal during the day to individuals who, if not for the alarm, would not have the time needed to escape the home or building before the fire spreads out of control. When installed as part of a house or building's fire alarm system, instead of as single, self-contained units, fire alarms provide additional protection whether inhabitants are inside the dwelling at the time of the alarm or not. When the monitoring station that the system is connected with receives the signal, it can send emergency medical help for individuals who need it, and fire department personnel can assist those who need help exiting the home or building. Also, as part of an overall system, one fire alarm that goes off triggers all the other fire alarms to go off, providing an alert to anyone within the vicinity.