We got a "Name unavailable" phone call this morning, and ignored it. They phoned back an hour later, and Anne told me to answer it. I did. Silence for a while, then a click and the call dropped into a noisy call center, really noisy. Guy with a slight Indian accent said "Good morning, this is Microsoft Technical Services".
I've read about this, heard plenty of stories. I'm not interested in playing games or leading them on. I just let out a bray of laughter, said "Big joke. Fuck off." and hung up.