The caller,[1] also referred to as a droid caller, control box, or owner, was a handheld transmitter device that was used to summon a droid or activate its restraining bolt.[2]
Callers were designed with three basic commands: "COME" called a droid forward, "STOP" forced it to halt, and "ORDERS" caused it to enact any commands, within the droid's operating parameters, given verbally.[2]
The Jawas of Tatooine often used callers to control their droids before selling them on. As a seven-year old child, Luke Skywalker created a makeshift droid caller in order to stargaze without his aunt and uncle's droids detecting him. It was confiscated when Owen Lars discovered him. Both Luke Skywalker and Han Solo both carried callers around 0 BBY. Luke used his caller to bring C-3PO out of hiding after R2-D2 departed to find Obi-Wan Kenobi.[3]