2004-11-06

The Bad Time Cell Phone

The other day a friend told me the time based on her cell phone's clock.

She said "your clock is two minutes fast." "Bullshit," I exclaimed in a nice way, "my clock is correct because it's synched with the USN clock in Colorado."

"But my phone has to be correct," she replied, "as my phone's time is set by my cell phone service."

Well, it turns out that she was wrong. We verified the time by calling the USN clock service in Washington D.C., and in fact her clock was about 90 seconds slow.

Happily, most providers of time information are getting more accurate. Here's my latest "clock accuracy matrix", using the USN telephone clock (202-762-1401) service as "accuracte":
  • AT&T GSM service (via Nokia 6820): 5 seconds slow
  • AT&T TDMA service (via Nokia 3360): 8 seconds slow
  • Verizon Time Telephone Service, Boston (617-637-1234): 20 seconds fast
  • SBC Time Telephone Service, Hartford (860-524-8123): 5 seconds slow
  • NIST Time Telephone Service (303-499-7111): Accurate
  • Cheapo Radio Clock from Target: Accurate
  • Verizon CDMA service (via Qualcomm 860): Accurate
  • WENH-TV XDS time (via Panasonic 4522): 1 second slow
  • 1-800-555-TELL service: Accurate
  • Verizon Time Telephone Service, Hawaii (808-565-9211): Accurate
  • Verizon Time Telephone Service, Washington D.C. (202-844-2525): Accurate
  • Unknown Telephone Service, Macdoel, CA (530-767-8500): Accurate


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