If I answer the phone, say hello, and there's a hesitation before anybody talks, I hang up immediately--that's the tell-tale sign it's likely computerized. I've had to warn friends and family they have to start talking as soon as I say hello. And, admittedly, I've gotten into trouble with my mother about this---she's a ferocious multitasker, especially on the phone-- (she admits it, and I've seen it)--and therefore is not necessarily paying attention when somebody answers.