It was designed by the Master in the guise of British Minister of Defence, Harold Saxon. The Master had an ulterior motive for putting the satellites in orbit, that is for the purposes of mind control, which was composed of a weak signal of four drumbeats, in which were coded a message telling humans to trust Saxon and vote for him in the upcoming 2008 UK general election.
In an alternative timeline, one which was erased a year after it diverged, the Network advanced to give humanity a global consciousness by using a low-level psychic field, and was utilised to make all fear the Master and so be subservient to him. However, this telepathic field also caused the Master's demise, as when all the slaves on Earth revolted against the Master shouting cries and thoughts of "Doctor!" due to the stories told to slaves by Martha Jones, the Tenth Doctor (who had been aged 900 years by the Master's laser screwdriver) was rejuvenated, became a temporary sort of god. The timeline was then erased when the Master was distracted by Jack Harkness's destruction of the paradox machine in the Doctor's TARDIS. (TV: The Sound of Drums / Last of the Time Lords)
Behind the scenesedit
The Visual Dictionary edit
It was a worldwide, mobile phone network that, from its 15 satellites, broadcasted the rhythm which allowed the Master to hypnotise Earth's population, giving him control over the people.