New ask Hacker News story: Ask HN: How to find current phone numbers?

Ask HN: How to find current phone numbers?
2 by wrp | 3 comments on Hacker News.
Even when I know the name and address of someone, it is nearly impossible to find their current phone number (in the USA). People search sites will give up to a dozen numbers for a particular name+address, but usually all of them are discontinued. If people don't maintain LinkedIn/Facebook/Twitter activity, how can you contact them?