- This article is about hand-held communication devices; for the Star Trek: Enterprise episode, please see "The Communicator".
A communicator, or personal receiver, is a hand-held communication device used by many species for person-to-person, person-to-ship, and inter-ship communications. Communicators usually transmitted on subspace frequencies.
Communicators were used by Starfleet landing parties and away teams; occasionally, communicators were used in situations where normal intraship communications were inaccessible (or inadvisable), during the 22nd and 23rd centuries. (TOS: "Mirror, Mirror", et al.)
By the 24th century, these communication devices were integrated into the standard uniform badges and became known as combadges. Users no longer had to speak directly into the communicator, but rather could activate and deactivate them with the touch of a finger. The combadge came into general use by 2344. (TNG: "Yesterday's Enterprise") Late-24th century communicators were composed of a crystalline composite of silicon, beryllium, carbon-seventy, and gold. (TNG: "Time's Arrow", "The Last Outpost")
In some cases, communicators served purposes beyond basic communication. For example, communicators were often used to allow transporter locks for beaming, thus acting as homing transponders. When used in tandem, two communicators could produce a sonic disruption by using sound beams to create a sympathetic vibration in an unstable object, such as a cliff face. Kirk and Spock used such a technique to ward off a party of angry Capellans on Capella IV in 2267. (TOS: "Friday's Child")
Among the items which were sold off on the It's A Wrap! sale and auction on eBay was a 22nd century communicator circuit board from the episode "Shockwave, Part II",  and a Klingon communicator, used in Star Trek: The Next Generation.