The Cloister Bell is a signal to the crew that a galaxy-scale catastrophe is occurring or a warning that they are in immediate danger. In short it is a call to "battle-stations." Though it is located in the Cloister Room, the Bell can be heard from anywhere in a TARDIS. Normally controlled by the Main Logic Junction, the Cloister Bell can also be rung from the Control Room by crewmembers. The High Council of Gallifrey can send a signal that will cause every Cloister Bell in the Universe to ring. Cloister Bells can be found on all TARDISes since the Type 22.