What was the original song that was remixed to make VOICES tilt-six Remix feat. Miku Hatsune?
according to the Vocaloid Wikia it's based on an EDM, non-lyrical song of the same name.
"VOICES" is a remixed Japanese song by tilt-six featuring Hatsune Miku. The song is based off of an EDM, non-lyrical song of the same name. The video was created as a collaboration between iXima, tilt-six and Sony to promote the new Sony XPERIA smartphone
the page list this youtube video as the original with the description saying
The official, original version of the song "VOICES", created to promote the Sony XPERIA smartphone.