Pretty much what the link says.... Vocal lines (and some sound effects) from Portal Turrets, both games.
And as a side note, I decided my Doctor Who ringer was too quiet (the spooky "Doctor's Theme" from Ten's years) so I downloaded 3 of the turret lines and then spliced them together into a ring tone...
So my current ring tone is... "I see you. Are you still there? Is anyone there?" played a couple of times.
tested it out and it sounds like it might be loud enough to get my attention.