There is lot of reason for being upbeat about the spread of answering machines, even if answering machine detection by dialers may not be as good as you might like.
Consider the following:
Imagine a campaign, where all the call outcome data remains the same except that no answers are replaced by answering machines, let's say being detected by agents. And the called parties are genuinely out. Options are:
If you take the view that called parties will use answering machines to screen out unwanted calls, then that too can be good news for the call center. You'll save the agent time spent in making the unwanted pitch, and even if you retry the number several times, you are likely to still be better off in terms of overall performance, because of shorter ring times for answering machines compared with no answers.