Tue 28 February 2017
Nobody likes you when you’re 23 /
And are still more amused by prank phone calls /
What the hell is caller ID?
Blink-182, “What’s My Age Again?”, 1992
You probably already know that Caller ID is useful, and that it can be faked. If you want to know how it works and how it fails, read on.
Once upon a time (prior to 1980-2, when AT&T was broken up), everything was simple. All calls in the United States, to a first approximation, were handled by AT&T or one of its daughter companies. They kept track of who …