EarPod

An EarPod was a device from a parallel universe, created by Human genius John Lumic. They could be used to read minds, control them, and add information into them (for example a daily joke). They were used as the alternate universe's alternative to mobile phones. (DW: Rise of the Cybermen)

The use of EarPods to control minds was used to cause them to be Upgraded into Cybermen (DW: The Age of Steel). When the Cybermen entered this universe, the earpeices of the Torchwood Institute - specifically, Torchwood 1 - allowed control in a similar way, paving the way for the Battle of Canary Wharf. (DW: Army of Ghosts)