The communicator is a fictional device used for voice communication in the fictional universe of Star Trek. As seen in at least two instances, the Original Series episodes "Tomorrow Is Yesterday" and "Day of the Dove," it can also serve as an emergency signaling device/beacon, similar to a transponder. The communicator allows direct contact between individuals or via a ship's communication system. The communicator was designed by Wah Ming Chang, who also designed other Star Trek props such as the Phaser and Tricorder, as well as the first Romulan ship. The communicator in the Star Trek universe surpasses the capabilities of modern mobile phone technology, the prototypes of which it inspired. It allows crew members to contact starships in orbit without relying on a satellite to relay the signal. Communicators use subspace transmissions that do not conform to normal rules of physics in that signals can bypass EM interference, and the devices allow nearly instantaneous communication at distances that would otherwise require more time to traverse. In Star Trek: The Original Series (TOS), communicators functioned as a plot device, stranding characters in challenging situations when they malfunctioned, were lost or stolen, or went out of range. Otherwise, the transporter could have allowed characters to return to the ship at the first sign of trouble, ending the storyline prematurely. Development of communicators Throughout Star Trek: Enterprise and Star Trek: The Original Series, on-ship communication is achieved via communicator panels on desks and walls, and sometimes through the use of videophones. While formed into a landing party, the crew carried hand-held communicators that flip open. The top section contains a transceiver antenna and the bottom contains user controls, a speaker and a microphone. The device was designed and built by Wah Chang, who also built many of the other props used in the series. Wrist-worn communicators were used in Star Trek: The Motion Picture and remained in use by some Starfleet installations and vessels during the time of The Wrath of Khan. However, the traditional handheld communicator returned in later films. The reason for the switch was not explained, but the non-canon source Mister Scott's Guide to the Enterprise offered the explanation that Starfleet discontinued use of the wrist-worn communicators when they were determined to be prone to repeated failures after suffering minor impacts. In Star Trek: The Next Generation (TNG) and later series, Starfleet officers and enlisted personnel wear small communicator