Ask HN: Why has online directory assistance (phone lookup) become useless?

If you've tried to look up a residential phone number on the web in the last few years, you've surely noticed that it has been useless. You get no information or spammy/scamly results even though a physical telephone book--assuming you still receive such a thing--still does have correct information for landlines.

The results of a reverse phone lookup are worse than useless because of a recent trend of bizarre sites that list completely false names and addresses for every 10-digit US/Canadian phone number. They don't even have ads, so I don't understand what they're getting out of listing fake information, and why Google doesn't push down their rank.

So my question is Why happened to online phone info? Are landline phone companies no longer making directory information available? I've heard that cellular companies do not publish any directory information (is that right?), but there are still millions of residential landlines. What happened to that data?