What Is A Code 4? Firefighter Radio Codes

You have probably heard different radio codes throughout your life, most likely in movies and television shows. But have you ever wondered what these radio codes mean?

Radio codes, or emergency service response codes, represent different kinds of emergencies. In emergency situations where time is of the essence, these radio codes alert authorities and convey meaning in as little communication as possible.

What Is A Code 4 Firefighter Radio Codes And When They Are Used.

In the US, radio codes are universal among emergency medical services (EMS), such as paramedics and firefighters.

Given the radio code, the receiver will know what is happening, the urgency level of the emergency or condition of the patient concerned, and how to respond.

So, what exactly are the different radio codes?

What Are Firefighter Radio Codes?

Firefighter radio codes represent different emergencies, communicated between firefighters and other emergency medical services, such as paramedics.

There are several radio codes, each representing a different level of emergency and how the receiver should acknowledge it.

The radio codes can report that an emergency response is needed, or that the medical situation is under control.

What Is A Code 4?

A Code 4 means that the situation is under control and no further assistance is needed. In other words, there are enough responders on the scene, and that the receiver does not need to send any further personnel or vehicles.

Code 4 also signifies the end of the call.

Code 4 is not widely used by fire departments and emergency medical services, however. Whether it is used or not depends on the department itself and the location.

Many departments prefer to simply use Codes 1, 2, and 3.

For this reason, the person calling a Code 4 must make sure beforehand that the code applies to that department or area.

What Is A Code 3?

A Code 3 means that urgent assistance is needed. Referred to as a “hot response”, Code 3 means that the situation is life-threatening for the patient and that it should be treated as a top priority.

In this case, there might be several casualties on the scene.

All responders should also travel quickly to the scene as soon as possible, using flashing lights and sirens.

Code 3 is high priority and the most urgent of all the radio codes.

What Is A Code 2?

A Code 2 means that there is, or might be, an emergency on the scene. 

Sometimes, a Code 3 can be re-reported as a Code 2 once further assistance arrives and assesses the situation. In this case, the radio message would instruct the receiver to “reduce code”. 

A Code 2 warrants that assistance should be provided, however it does not have to be treated urgently. EMS vehicles can make their way to the scene without using flashing lights and sirens.

A Code 2 is more of a high priority than a Code 1, but not as urgent as a Code 3.

What Is A Code 1?

A Code 1 is referred to as a “cold response”. This means that the situation is of low priority, and that further assistance is not urgently required.

Code 1 is the least urgent of all the emergency radio codes.

However, while Code 1 is the lowest priority of all the radio codes, it does not mean that the situation or emergency will not be acknowledged or actioned upon by the receiver.

What Are Priority Terms?

Now that you know the four different Codes used in emergency medical services, what are Priority Terms?

Priority Terms are sometimes used among emergency medical services - paramedics and firefighters - in conjunction with radio codes listed above. This helps to provide more details about the situation at hand and what the possible emergencies are and what they involve.

With a better understanding of the situation, the receiver will be able to respond more specifically.

Again, the usage of Priority Terms depends on the EMS department and the location of the department.

Priority 1

Priority 1 signifies a “DOA”. This means that the patient is dead on arrival, or a trauma patient. CPR might be required, depending on the patient’s condition.

Priority 2

Priority 2 means that emergency assistance is required, or that the situation is an emergency and should be treated with urgency.

In this case, assistance should arrive as quickly as possible using flashing lights and sirens.

Priority 3

Priority 3 means that the situation is not an emergency, but the patient on the scene needs to be transported for further medical attention.

Priority 4

Priority 4 signifies that the situation, or emergency, is under control. 

It is more of an update than a call for action. In other words: no further assistance, or action, needs to be organized by the receiver.

Priority 5

Priority 5 is the most urgent of all the Priority Terms, despite the order of urgency de-escalating from Priority 2 through to Priority 4.

Priority 5 means that there are multiple casualties on the scene, and that emergency assistance is urgently required.

As Priority 5 can be interchangeable with a Code 3, it is the reason Priority Terms are not used by all EMS departments.

What Are Ten-Codes?

Firefighter radio codes

What about ten-codes? What are they?

You are sure to have heard these in movies and television shows when a police officer reaches for their radio, or is contacted via the radio in their police car.

Ten-codes, also 10-codes, or brevity codes, are used among police officers and police departments in the US.

Similar to EMS radio codes and Priority Terms, they convey a situation, request, or update, expressed in as little communication as possible.

There are over 100 ten-codes. However, their usage has dwindled over the years, due to the sheer number of ten-codes and the fact that some ten-codes have adopted different meanings, used exclusively depending on the state or police department.

As a result, there is no “official” or standardized ten-code list in the US. And, in 2006, the US federal government urged the discontinuation of ten-codes for all police officers and police departments.

Despite this, ten-codes are still used by some police officers - mostly the more “popular” and more universal ten-codes - often among one another as colleagues or more simply just for convenience.

See below for some meaning behind some of the most widely used ten-codes.

List Of Popular 10-Codes

10-0 - Use caution (regarding a citizen or location)
10-1 - Can’t understand (radio signal is not clear)
10-2 - Can understand (radio signal is clear)
10-4 - Acknowledged or affirmative
10-6 - Responding police officer is busy
10-8 - Responding police is available, or has just finished a previous call or task
10-9 - Repeat the message
10-9 - Negative
10-12 - Stand by (wait until further notice)
10-16 - Domestic disturbane
10-18 - Return to the station
10-20 - Location request
10-21 - Request or instruction to call
10-22 - Disregard previous message
10-23 - Arrived on the scene
10-27 - Check license of citizen
10-28 - Check license plate
10-29 - Check for wanted or stolen vehicle
10-31 - Crime in progress
10-32 - Person with gun; gun spotted
10-37 - Suspicious person or vehicle
10-41 - On-duty, police officer starting shift
10-42 - Off-duty, police officer finished shift
10-94 - Reckless driving

Remember: 10-codes are not the same for every police department or location.

Are Radio Codes Still Used?

Radio codes - most predominantly Code 1, Code 2 and Code 3 - are used by emergency medical services, including paramedic teams and firefighter.

Priority Terms, which provide more detail to the above radio codes, are used depending on the EMS department, or fire department, and its location - where the use of Priority Terms might be favored.

Ten-codes, used by police officers, are not widely used anymore.

This is because the number of ten-codes has increased over the years (there are more than 100 ten-codes), which has resulted in general confusion, as well as multiple meanings of ten-codes between different police departments and states.

As a result, the US federal government urged the discontinuation of ten-codes by all police departments in 2006.

Since then, there has been a gradual, but not yet widespread, shift towards using plain language over police radio as a replacement for ten-codes.

You might still to continue to hear ten-codes in movies and television shows, purely for stylistic reasons. Police officers may still use ten-codes among one other in their specific department or city as a habit or simply for convenience.


In conclusion, radio codes are used by firefighters and paramedics (emergency medical services) in the US. These codes provide a simple way to communicate a situation or level of emergency for a patient or patients, and then what is required in terms of a response.

The response could be further assistance, or a simple acknowledgment from the receiver.

To quickly recap:

Code 1

Code 1 is a “cold response”, and means that the situation, or patient, is not a high-priority emergency. Other emergency medical services do not have to rush to the scene.

Code 2

Code 2 is more urgent than a Code 1, but still means that the situation is not high-priority. Emergency assistance should come to the scene, but does not have to make use of flashing lights and sirens to get there.

Code 3

Code 3 is the most urgent of the radio codes - a “hot response”. It signifies that the emergency is life-threatening, or involves multiple casualties, and that assistance should arrive as soon as possible (using sirens and flashing lights).

Code 4

Code 4 is not widely used; it is only used by some EMS departments. It means that the emergency is under control and that no further assistance is needed.

As for Priority Terms, these provide more information to the receiver than Code 1, Code 2, and Code 3.

For example, Priority 1 means that the patient is DOA, Priority 2 means that emergency assistance is required, while Priority 5 means that there are multiple casualties on the scene. Not all emergency medical services use Priority Terms.

10-Codes are used by police officers in a similar way to communicate information over radio in as few words as possible. However, 10-codes are no longer widely used.

This is because the large number of 10-codes has become confusing, with some of them having multiple meanings, differing between state or police departments.