Transdimensional portal

Transdimensional portals were the transport used by the Threllips. It required a projector, tertiary signals and aligned sub-space modifiers to work. It allowed the transport of objects or information.

In 1982, Vengorr and Thon were sent to Earth to set up a transdimensional portal to allow the Threllips to invade. The Eighth Doctor was able to distract them and reprogram it. When Vengorr and Thon went through it, they were transported to one of the moons of Mordelius Prime. (BFA: Living Legend)