Back when CB radios first started, they had tubes, and tubes had to "warm up" before transmitting. So, after keying the mic, the user had to pause a few seconds or that part of his or her transmission would be lost to the listener. Thus, the so-called 10 codes were developed to automatically insert that necessary pause at the beginning of the transmission (during the time it took to say the "10" part of the code, before the important informational part of the code was given). Modern equipment doesn't have that problem, so the trend for modern day users is to drop the 10 codes altogether and use ordinary language for communication. Here are the most common:

• 10-1    Receiving Poorly
• 10-2    Receiving Well
• 10-3    Stop Transmitting
• 10-4    Okay, Message Received
• 10-5    Relay Message
• 10-6    Busy, Stand By
• 10-7    Out of Service, Leaving Air
• 10-8    In Service, subject to call
• 10-9    Repeat Message
• 10-10  Transmission Completed, Standing By
• 10-11   Talking too Rapidly
• 10-12   Visitors Present
• 10-13   Advise weather/road conditions
• 10-16   Make Pickup at…
• 10-17   Urgent Business
• 10-18  Anything for us?
• 10-19   Nothing for you, return to base
• 10-20  My Location is ……… or What’s your Location?
• 10-21   Call by Telephone
• 10-22   Report in Person to _____
• 10-23   Stand by
• 10-24   Completed last assignment
• 10-25   Can you Contact ______
• 10-26   Disregard Last Information/Cancel Last Message/Ignore
• 10-27   I am moving to Channel ___
• 10-28   Identify your station
• 10-29   Time is up for contact
• 10-30   Does not conform to FCC Rules
• 10-32   I will give you a radio check
• 10-33   Emergency Traffic at this station
• 10-34   Trouble at this station, help needed
• 10-35   Confidential Information
• 10-36   Correct Time is _____
• 10-38   Ambulance needed at _____
• 10-39   Your message delivered
• 10-41   Please tune to channel ___
• 10-42   Traffic Accident at _____
• 10-43   Traffic tie-up at _____
• 10-44   I have a message for you (or ____)
• 10-45   All units within range please report
• 10-50   Break Channel
• 10-62   Unable to copy, use phone
• 10-62sl  Unable to copy on AM, use Sideband Lower (not an official code)
• 10-62su Unable to copy on AM, use Sideband Upper (not an official code)
• 10-65   Awaiting your next message/assignment
• 10-67   All units comply
• 10-70  Fire at _____
• 10-73  Speed Trap at _____
• 10-75  You are causing interference
• 10-77  Negative Contact
• 10-84  My telephone number is ____
• 10-85  My address is _____
• 10-91   Talk closer to the Mike
• 10-92   Your transmitter is out of adjustment
• 10-93   Check my frequency on this channel
• 10-94   Please give me a long count
• 10-95   Transmit dead carrier for 5 sec.
• 10-99   Mission completed, all units secure
• 10-100  Need to go to Bathroom
• 10-200  Police needed at _____