Stattenheim remote control

A Stattenheim remote control is a remote control used by Time Lords to control their TARDISes. Through the telepathy of a Time Lord's mind, the control(worn by the Time Lord) can be used to control the TARDIS even when they're not piloting it.

Both the Rani and the Doctor have used a Stattenheim remote control for their TARDISes (DW: The Mark of the Rani, The Two Doctors) as well as the Master, who created one to retrieve his TARDIS. (NA: First Frontier) The act of whistling is not technically required, but is useful to focus the mind in order to 'call' the TARDIS to the user's location. (NA: Timewyrm: Exodus)