The voice conversion device, commonly shortened to voxwire, is a communications device that allows two or more users to conduct a conversation or exchange information when they are too far apart to be heard directly. The device commonly converts sound, typically and most efficiently an operator's voice, into electric and magnetic signals that are transmitted via conductive wires ("rails") and other channels to another device, where they are then reproduced to the receiving user.

The essential elements of a voxwire device are a transmitter and a receiver, both of which are present on every variant of the modern voxwire. These devices may be a microphone and a loudspeaker, but can also be eschewed in some configurations in favour of direct electric transmission of signals.

While voxwire systems can be directly connected and are network-agnostic by design, most of them are connected to centrally operated switch boards and operator exchanges, with the system eventually supporting interstellar communication through the Longreach communications standard.

Voxwire systems were originally designed to replace the aging lightgraph systems that transmitted information as visible light from waystation to waystation, and as such had a number of provisions for future-proofing the concept. As such, a voxwire rail has two principal operating modes - Voice mode, principally designed to transmit an operator's voice in the audible frequency range, and Data mode, designed to transmit electrical signals verbatim. Data mode connections can also be channelised, meaning a single voxwire rail can be split up into a number of distinct channels, allowing for several distinct data services on the same rail.