A bit off base, last year US consumers referenced the print Yellow Pages over 13.4 billion times and iPhones aren't the norm for most people. It might surprise you to know that many people don't even have access to the Internet at work.
FYI, YP publishers also have online versions AND provide content to other search sites. It comes down to choice, or sometimes just the time of day, the room you're in or the way you want to search. Small businesses rely on the YP in all its formats to get buyers, not browsers. Full disclosure, I work for the Yellow Pages Association and more information can be found at www.ypassociation.org.
 

Millions of small businesses spend their hard earned advertising dollars to be in those books. Think they would be doing that if it wasn't generating a lot of business for them???
 

S Hobbs and kenc make strong points. My brother has a recruiting business in a high tech area and he gets over 30 calls per month from his Yellow Book print ad and lots of clicks from the internet version as well.
I use the internet for research about products (and reviews), but I still find local businesses the old fashion way. And like SHobbs said, I do not surf the net at work.