I really like the National Do Not Call Registry, but something struck me today: why didn’t phone companies develop analogous services way before the government registry was established? Imagine how popular a service to prevent telemarketers would have been before 2003. It would have been very lucrative for phone companies to offer an option to stop telemarketers from calling their customers, especially in terms of market share. There must have been some reason why such services were not offered, but I can’t come up with one. I have ruled out technical limitations and legality issues because phone companies are (and were) able to block specific numbers. I remain baffled.