Hypercube

Hypercubes were a type of communication technology used by the Time Lords which resembled cubes. (EDA: The Ancestor Cell)


 * Presumably, the Doctor, seen assembling the components to summon the Time Lords about the War Lords, used a hybercube. (DW: The War Games'')

Behind the Scenes
In Real World science, a hypercube means a higher-dimensional analogue to a cube, the former have having four, the latter having three dimensions.