Two-way communications, the low-tech way:

A company called Tiger News delivers two newspapers to our home every morning. They are a reliable service, able to meet our flexible requirements when we're away from home. We like them, although they are hard to communicate with. They have a phone number that reaches an answering machine. When the machine is “on” it rings about seven times before picking up, long enough to weed out a few over-eager callers. But the machine is only on a few hours each morning after delivery time. Mostly, when you call, it rings twenty times and then says “the machine is off” and hangs up. Now I understand this rather poor method of communication. Newspaper delivery is a low-overhead business, and anything Tiger News wants to do to keep their costs down is probably okay with me.

But this morning I really wanted to leave a message, because they delivered only one paper, not two. I called, and the phone rang and rang. “Aha,” I said to myself, they've turned their machine off, because they are expecting to get hundreds of calls about the missing paper. That paper must have come to them too late to deliver on time; I'll just wait. And an hour later, the other paper turned up. So I consider that their answering machine managed to have a useful dialog with me, even though it really didn't say anything.