Intercom system (school)

In a school, an intercom system is a kind of PA system used to make announcements during the school day. A school intercom system usually includes an intercom in each classroom, the hallways and other rooms of the school, and intercom call button in each classroom where the teachers can call the office. With modern intercom systems, a special kind of telephone or a standard telephone which is connected to the telephone system in the school, these phones can have access codes assigned to them to control who may have access is the main control of the intercom system and with that telephone, the person using it can talk on the intercoms of any classroom by dialing the room number of that classroom.(also some use code made by the main intercom)