You might have seen a fire alarm pull station before - simple, little red boxes, but with an important role in fire prevention. Most public buildings have them. Their purpose is to let people alert the fire department if they are sure a fire is breaking out.
Different alarm pull stations have different means of activation. Some require that you pull a T shaped handle, while others require a two step process - which is to prevent accidental calls to the fire department. Some pull stations have a glass covering, requiring you to break the glass first, while others have a lever to push, or handle to turn.
Don't get confused by the methodology though. Their purpose is still the same, and that is to give people a direct link to the fire department to report a fire (or potential fire), without having to reach for the phone.
Fire alarm pull stations are connected to the control panel only when the fire detection units are set to automatically detect fire or smoke. But in most buildings, the fire sensing devices are not connected to the pull station. So pulling them will not set off the smoke alarms or the sprinkler system. This is to prevent misuse and reckless alerts to the fire department.