They use a computer generated voice for their calls.
It is a pleasant sounding 20 something year old female north american presenting voice. When I called them on being a computer they indicated it was a computer generated voice only and that they were live and talking into a microphone. So essentially they are using the human labour to allow them to adapt to the varied nature of a phone conversation but are white washing the voice.
I can't even imagine how dehumanizing the labourer must feel in this situation.