Vortex manipulator

A vortex manipulator was a form of basic time travel developed by the Time Agency of the 51st century.

Biography
The accuracy of travel the vortex provides is unclear, Jack Harkness arrived in 1869 when aiming for the late 20th century. A setting on the sonic screwdriver is able to enhance the accuracy of the travel path, as the Doctor is able to use it to guide Jack and Martha from the future back to when they had last left.

Although it was generally used by the Agency, the Family of Blood stole one to follow the Doctor around the universe. (DW: Human Nature / The Family of Blood) The Doctor considered it very primitive compared to a TARDIS, describing his TARDIS as a "sports car" to Jack Harkness's "space hopper". The TARDIS controls include a vortex manipulator. (DW: Attack of the Graske)

Presumably the vortex manipulator created some sort of shield to protect an Agent from the side effects of an unprotected journey through the vortex. This did not, however, prevent some considerable discomfort for the user, as shown by the Doctor, Jack and Martha's responses upon arriving in London. (DW: The Sound of Drums )

Jack Harkness had his manipulator housed in a Time Agency wrist strap. (DW: Utopia)

When someone sends a hologram to an manipluator the manipulator beeps till you open it. (TW: Kiss Kiss, Bang Bang)

While jacks vortex manipulator was still inactive jack was able to put in a teleport base code to which was housed in the indego device which Martha Jones had, the code was 4 and 9 these to numbers kept comeing up on the panel, it was later de-activated by the The Doctor (DW: The Stolen Earth)

Jack was wearing his Vortex Manipulator during the explosion of Torchwood Three, but it seems they are virtually indestructible. (TW: Children of Earth: Day Five)

Functions

 * Vortex manipulation to facilitate time travel (DW: Utopia, The Sound of Drums)
 * Communication between users, listening to radio broadcasts, including storage of messages (TW: Kiss Kiss, Bang Bang, DW: The Sound of Drums)
 * Projection of holograms (DW: The Empty Child, TW: Kiss Kiss, Bang Bang, Fragments) 
 * Teleportation (DW: The Sound of Drums, Last of the Time Lords, The Stolen Earth Children of Earth)
 * Tracking of life signs (DW: Journey's End, Bad Wolf)
 * Remote control of electronic devices (TW: Everything Changes, Exit Wounds,)

Users

 * Captain Jack Harkness
 * Captain John Hart
 * Grey
 * The Family of Blood (stolen)

Behind the Scenes

 * Its unknown if the Time Agency actually created the vortex manipulator its just assumed but as its made in the 51st century it may be easier in the future to make technology like this.