Over at Cosmic Variance, JoAnne tells a story about dialing Pi on the phone:

Several years ago, before pi-day was famous, a student called the phone number associated with the digits in pi that appear after the decimal point, i.e., 1-415-926-5358. Apparently this is rather common now, and in fact, appears to be promoted as a mnemonic for the first 10 decimal places for those folks we need to have those numbers handy at all times. But this story happened in earlier times, back before the Bay Area split into several area codes. And, as the clever reader has already guessed, that student reached the SLAC main gate. How cool to phone pi and reach the main gate of a major national scientific research laboratory!

I remember the Cesium atomic clock frequency as a phone number: 919-263-1770. It should be a number in the Raleigh, NC region, but there is no listing for it. I’ve never actually called it.