Humane Soc. Probably not what you think.
I.R.S. Try any of these acronyms on for size.
Who’s on the Line? Increasingly, Caller ID Is Duped. (The New York Times, 11/23/2011)
Different headline in the online edition.
Excerpt: "You don’t know who is on the other end of the line, no matter what your caller ID might say,” said Sandy Chalmers, a division manager at the Department of Agriculture, Trade and Consumer Protection in Wisconsin.
Then there's this USA Today article from 3/1/2006: