Dimensional transporters, also known as parallel world transporters, were pieces of teleportation technology.
When the Cybermen made their way into the Doctor's universe through a crack in the Void, they began a plan to invade it and convert humanity into Cybermen. Mickey Smith had followed them through, (TV: Army of Ghosts) leading the way for others such as Jake Simmonds, Pete Tyler and the Preachers to follow, and help defeat the Cybermen. (TV: Doomsday) Pete later used it to save his daughter from being pulled into the Void. (TV: Doomsday) Rose travelled from Pete's World to the Doctor's universe during the Dalek invasion of Earth, hoping to the find the Tenth Doctor. Mickey and Jackie also followed Rose, and saved Sarah Jane Smith from a squad of Daleks. (TV: Journey's End)