10-4 Isn't the Only Number Code That Police Use Over Their Radios — What They All Mean

"10-4," "roger that, over," and "copy." What do all these radio phrases mean and how can you use them to communicate?

Alex West - Author

Mar. 21 2024, Published 8:23 a.m. ET

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Speaking over walkie talkies is fun and exciting at first. Ignoring the fact that we all walk around with a phone nowadays, there's definitely something special about radio and walkie communication.

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Quickly, though, you'll learn that it can be a little confusing to understand each other or accidentally talk over each other. So, there's a few code words to help keep things straight, including the famous "10-4."

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What does 10-4 mean?

You may have heard 10-4 being used on those cop shows and haven't thought much about it. As it turns out, 10-4 is just one of a lengthy list of "10 codes" which is a system meant to make communication easier.

Saying "10" immediately tells the receiver that you're about to use some code and then the following number communicates what that actual message is.

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In essence, 10-4 just means "message received" or "OK." There are other ways to communicate the same thing over radios and walkie talkies that don't require the 10 codes.

It's also common to say "copy" or "over." "Copy" mainly means a simple "OK" and is similar to "10-4." An "over" is used as a way to communicate your sentence or thought is over. You'd use it at the end of a sentence and it's helpful to prevent those on the radio from talking over each other or cutting out.

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If someone starts their sentence with "roger," just know that they aren't addressing some random guy named Roger. Instead, they're letting you know they heard and understood what you were saying and, often, they'll follow it up with their own sentence.

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What are the 10 codes?

As mentioned, there's a long list of 10 codes with specific meanings. If you're going to be using radios to communicate frequently, it might be beneficial to learn and memorize them all.

Here's the complete list of 10 codes:

  • 10-0 – Use caution
  • 10-1 – Bad signal
  • 10-2 – Good signal
  • 10-3 – Stop transmitting
  • 10-4 – Message received
  • 10-5 – Relay
  • 10-6 – Busy
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  • 10-7 – Out of service
  • 10-8 – In service
  • 10-9 – Repeat
  • 10-10 – Negative (no)
  • 10-11 – Animal issue
  • 10-12 – Stand by
  • 10-13 – Weather conditions
  • 10-14 – Message
  • 10-15 – Civil disturbance
  • 10-16 – Domestic disturbance
  • 10-17 – Enroute (on the way)
  • 10-18 – Urgent
  • 10-19 – Go to station
  • 10-20 – Location
  • 10-21 – Call [name]
  • 10-22 – Disregard
  • 10-23 – Arrived
  • 10-24 – Assignment complete
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  • 10-25 – Report to [place/person]
  • 10-26 – Detaining suspect
  • 10-27 – License info
  • 10-28 – Vehicle info
  • 10-29 – Records check
  • 10-30 – Unauthorized radio use
  • 10-31 – Crime in progress
  • 10-32 – Person with a gun
  • 10-33 – Emergency
An officer of New York Police Department detains a man at a pro-Palestinian demonstration
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Is "420" really a police code?

With the 10 codes established, is it possible that there's a hidden 4 code that has 4-20? Rumors have long spread that the infamous 420 number, which refers to marijuana, started from the cop code of the drug.

It turns out this is a myth. Verify This discovered that there aren't any codes in laws or police departments that refer to smoking weed as "420." The association with the word is just something that happened organically.

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