The Jedi beacon, located in the central security station of the Jedi Temple, functioned as a communication device for all Jedi across the galaxy. Generally, it was designed to transmit a signal, calling all Jedi back to their home on Coruscant. Its most basic function was a simple alert, a consistent pinging sound. However, it also had more advanced features, enabling the transmission of detailed text and holographic communications.
During a lesson for younglings at the Jedi temple, Caleb Dume questioned whether it could be programmed to caution Jedi against returning to Coruscant. While some were taken aback, Obi-Wan Kenobi conceded that there might be unforeseen circumstances where such a warning would be crucial.
During the siege of the Jedi Temple, Darth Vader utilized the beacon to summon the Jedi back to Coruscant. The intention was to draw any Jedi who had survived Order 66 to the Temple, unaware of the true situation, where the troopers stationed there would kill them. However, Kenobi modified the transmission, replacing it with a holographic message from himself, warning all surviving Jedi to stay away. At least two Jedi, Caleb Dume and Cere Junda, received Kenobi's message. Caleb, traveling in hyperspace towards Coruscant, was alerted and prevented from landing on the planet. Junda received the message and saved the transmission to a holocron.
The Jedi beacon was initially featured in the 2005 movie Star Wars: Episode III Revenge of the Sith.