Vox-caster

A communications array, similar to a radio, that can be as small as helmet mounted links to massive banks of equipment at the HQ. Usually a squad or platoon will have a link to HQ via one vox unit and smaller relays for trooper-to-trooper communications. Command units usually use more complex versions of vox casters-known as master voxes. These can receive and transmit on multiple frequencies at once, making them ideal for coordinating many squads at once. In absence of any vox communications, troopers are taught to sign to each other when in battle.

Space marines and Sisters of Battle (and high ranking members of the Inquisition, Adeptus Mechanicus) have miniature vox-casters built into their power amour (or cranium in the case of the Adeptus Mechanicus). Most of these are short ranged and used only for squad to squad communication.