10-4 CB lingo. Help me out here.

[Brian37]

I know 10-4 means "Message received and understood". But my question is how did that start and why was 10-4 assigned to that meaning? 

And as an aside,  back when I was a kid, my mom bought a used USPS  mail jeep, and she had a CB in it. My handle back then was R2D2.

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Nevermind folks, found it. But click if interested.

https://www.dictionary.com/e/slang/10-4/

[Gawdzilla Sama]

https://en.wikipedia.org/wiki/Ten-code

[arewethereyet]

Long before CBs became a thing that truckers and the average Joe had my dad had a two-way radio with the base station and a HUGE antenna tower at the home office and he had a radio in his truck. He was a veterinarian who mostly traveled from farm to farm treating dairy cattle and hogs. We were trained early how to use the radio. I still remember the routine. The call letters were KLW272 - there was no nickname like later on the CB when many people had access to the same radio bands. Dad would call in and we would either respond with new calls that had come in or we would say 'nothing doing'. Every call ended with 10-4 from either dad or whoever at the house had answered the call. I always saw '10-4' as being similar to hanging up the phone - this conversation is over - nothing more to follow.

[Brian37]

Extra credit, what was the phrased used to call out to other CB users to make sure your equipment was working or if you had an emergency?

And, an aside, there was also a 10-3.

[BrianSoddingBoru4]

Extra credit, what was the phrased used to call out to other CB users to make sure your equipment was working or if you had an emergency?

And, an aside, there was also a 10-3.

'I've got a loverly bunch of coconuts'?

Boru

[Gawdzilla Sama]

 I always saw '10-4' as being similar to hanging up the phone - this conversation is over - nothing more to follow.

Odd. I see it as "Got that." or "Wilco." Not a capper per se.

[arewethereyet]

Extra credit, what was the phrased used to call out to other CB users to make sure your equipment was working or if you had an emergency?

And, an aside, there was also a 10-3.

If you click on the link Zilla provided, you will see there are several 10 codes.

As for an emergency, there are quite a few depending on the nature of the emergency.

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 I always saw '10-4' as being similar to hanging up the phone - this conversation is over - nothing more to follow.

Odd. I see it as "Got that." or "Wilco." Not a capper per se.

Just telling you how it was when dealing with dad.

10-4 meant this interaction is over.

[onlinebiker]

CB band - what happens when bureaucrats legislate what should be left to people with real knowledge of the matter.

A waste of frequency.

A frequency that under the right sunspot cycle is capable of worldwide communication on just a few watts of power - given to a bunch of yahoos with no real need for it.

Citizens band should have been over 200 mhz - so it could be used locally.