You’re staring at your smartphone. It’s synced to an atomic clock via GPS, updating itself every few milliseconds without you ever lifting a finger. It is, for all intents and purposes, the most accurate timekeeping device in human history. So, why on earth would anyone still need to know what is the telephone number for time?
It feels like a relic. It’s like asking for a physical map in the age of Google Earth. But honestly, the "Talking Clock" is one of those weird, stubborn pieces of infrastructure that refuses to die, mostly because it’s surprisingly useful when the digital world glitches out.
If you’re in a rush and just need the number: in the United States, the most famous one is (303) 499-7111. That’s the dedicated line for the National Institute of Standards and Technology (NIST) in Boulder, Colorado. If you’re in the Navy or just prefer their vibe, the U.S. Naval Observatory (USNO) runs a similar service at (202) 762-1401.
The Ghost in the Machine
Most people under the age of thirty have probably never dialed a number to hear a robotic voice tell them it’s "exactly twelve o'clock and forty seconds." It sounds like something out of a fallout shelter. But for decades, this was how the world stayed synchronized.
Before the internet, if your wall clock stopped or you needed to set your watch, you picked up the rotary phone. You’d hear a series of ticks, a beep, and a voice. It was authoritative. It was the "official" time.
Today, we take synchronization for granted. Your laptop, your oven (sometimes), and your car all talk to the cloud. But the cloud can be wrong. Networks have latency. Sometimes, you just need a source of truth that doesn't rely on a handshake between your router and a server in Virginia.
What is the Telephone Number for Time? (The NIST vs. USNO Rivalry)
It’s actually kinda funny that we have two competing "official" times in the U.S.
The NIST number—the 303 area code one—is managed by the same folks who handle the WWV and WWVH radio stations. When you call (303) 499-7111, you are hearing a broadcast that is literally coming from a bank of atomic clocks. They use cesium oscillators. These things are so accurate they won't lose a second in millions of years.
Then you have the Naval Observatory. Their number, (202) 762-1401, is the Master Clock of the United States. While NIST is about civilian standards and industry, the Navy is about navigation and defense. If you’re a sailor or a pilot, the USNO is your North Star.
There’s a catch, though.
Calls to these numbers aren't usually toll-free. If you’re calling from a landline or a cell plan with limited minutes (if those still exist), you’re paying for the long-distance call to Colorado or D.C. NIST actually limits calls to three minutes because, honestly, how long do you need to listen to a clock?
Why do people still call these numbers?
You’d be surprised. NIST handles millions of calls a year.
Amateur radio operators (ham radio enthusiasts) use it to calibrate their equipment. Scientists use it as a backup verification. And then there are the people who just like the nostalgia. There is something deeply grounding about hearing a calm, steady voice tell you the exact moment the world is living in. It feels more "real" than a digital readout on a screen.
Also, think about power outages.
When a massive storm knocks out the internet and the cell towers are struggling, a plain old telephone service (POTS) landline often still works. In those moments, when you’re sitting in the dark and your phone is dead, that "telephone number for time" is your only link to the schedule of the rest of the world.
The Local "Popcorn" Numbers
If you grew up in Northern California, you didn’t call Colorado. You dialed "POPCORN."
Literally. P-O-P-C-O-R-N (767-2676).
This was a service provided by Pacific Bell. In other parts of the country, it was T-I-M-E or some other mnemonic. Most of these local services have been shut down. They were expensive to maintain and, as everyone got a cell phone, the advertising revenue (the "This time is brought to you by..." part) dried up.
In 2007, AT&T killed off the local time-and-temperature numbers in California, ending an era. People were actually devastated. It was a piece of local culture that just vanished. Now, if you try to dial those old 767 numbers, you’ll likely just get a busy signal or a "number not in service" recording.
How Atomic Clocks Actually Work (Simply)
We say "atomic clock," and it sounds like something from a sci-fi movie with glowing green goo. It’s not.
Basically, an atom—usually Cesium-133—has a very specific vibration frequency when it’s hit with microwaves. It’s like a tuning fork that never goes out of tune. Specifically, it vibrates 9,192,631,770 times per second.
The "telephone number for time" is just the audio representation of that vibration. When you hear the beep, a computer has counted exactly that many vibrations and triggered the sound. It’s the closest humans have ever come to measuring the heartbeat of the universe.
The Latency Problem
Here is something the experts know that the average caller doesn't: the time you hear on the phone is technically wrong.
Wait, what?
Sound travels fast, but electricity and signals traveling through copper wires or fiber optics take time. If you’re in New York calling the NIST number in Colorado, the signal has to travel about 1,600 miles. That takes a few milliseconds.
Then there’s the delay in your own phone.
Digital cell phones have "vocoders" that compress your voice. This adds even more delay. If you’re trying to sync a high-precision scientific instrument, don't use the phone. Use a GPS disciplined oscillator. But if you're just trying to make sure your grandfather clock is mostly accurate? The 30-millisecond delay doesn't matter. You can't react that fast anyway.
International Time Numbers
It’s not just an American thing.
The UK has the "Speaking Clock." You dial 123 on any BT line. It started in 1936 and survived the Blitz. The voice is currently that of Alan Steadman, who won a competition to be the voice of time.
In Canada, the National Research Council provides a similar service. They have a long-distance line and a shortwave radio broadcast (CHU).
Australia had a famous one too—dial 1194. Unfortunately, Telstra shut it down in 2019. It was a sad day for Aussie watch-collectors. The decommissioning of these services is happening globally as "Network Time Protocol" (NTP) becomes the standard.
The Future of the Talking Clock
Is the "telephone number for time" going away?
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Probably. NIST and the USNO have both faced budget scrutiny. Maintaining old-school telephone lines for a service that is essentially redundant seems like an easy target for cuts.
But there’s a strong argument for keeping them.
They represent a "low-tech" fail-safe for a "high-tech" problem. In the event of a massive cyberattack on the Global Positioning System (GPS), we would lose the primary way we sync our power grids and financial markets. Having a terrestrial, telephone-based backup is a form of national resilience.
Plus, there is the accessibility angle. Not everyone has a smartphone. Not everyone can see a digital clock. For the visually impaired, being able to hear the time is a vital utility.
Actionable Steps for the Curious
If you want to experience this bit of living history before it’s gone, here is what you should do:
- Call the NIST: Dial (303) 499-7111. Listen to the background ticks. Notice how the voice gives the time in Coordinated Universal Time (UTC) first, then follow the instructions to figure out your local offset.
- Call the Navy: Dial (202) 762-1401. Compare it to the NIST. See if you can hear a slight delay between the two if you put them on speakerphone (it’s a fun, nerdy experiment).
- Check your Latency: Look at your computer’s clock while the phone is to your ear. See how closely they align. If your computer is more than a second off, your NTP sync might be failing.
- Shortwave Radio: If you really want to go down the rabbit hole, buy a cheap shortwave radio and tune to 5, 10, or 15 MHz. You’ll hear the NIST broadcast (WWV) coming directly from the ionosphere. It sounds like the end of the world, but it’s actually the most stable thing on the planet.
The telephone number for time is a bridge to an era when we had to seek out information rather than having it pushed to us. It’s a reminder that beneath our slick interfaces and 5G networks, there is a physical world of wires, atoms, and spinning gears keeping the seconds from slipping away.
Don't wait until the next big internet outage to find out if these numbers still work. Try them now. It’s a three-minute trip into the past that tells you exactly where you are in the present. It's oddly comforting to know that no matter how chaotic the news gets, the atomic clocks in Colorado are still just ticking away, one nine-billionth of a second at a time.
Next time someone asks you for the time, you’ve got a much better answer than just glancing at your wrist. You’ve got a direct line to the source. Use it while it's still there. Change is the only thing we can't stop, and eventually, even the talking clocks will go silent. For now, the line is open.
Sources for Verification
- NIST Physical Measurement Laboratory (Time and Frequency Division).
- U.S. Naval Observatory (USNO) Master Clock Department.
- BT Speaking Clock History (UK Archives).
- FCC records on the decommissioning of local 767 services.