The internal communications device was a piece of technology that emitted a powerful buzzing noise when activated. During 5 ABY, the Jedi Luke Skywalker encountered the protocol droid C-3PO at the Droid Repair Shop located on the moon Yavin 4, with the intention of readying the droid for a secret mission. Skywalker utilized his internal communications device to alert the Droid Modification Team that C-3PO was set to undergo a disguise.
The internal communications device made its debut in the initial book of the Jedi Prince series of junior novels, titled The Glove of Darth Vader, which was authored by Paul and Hollace Davids and released in 1992.