Emergency service response codes

Emergency service response code systems vary from country to country, with different methods used to categorize responses to reported events.
United States.
A Code 3 Response in the United States is used to describe a mode of response for an emergency vehicle responding to a call. It is commonly used to mean "use lights and siren".
In some agencies, Code 3 is also called a Hot Response. Code 1 is also called a Cold Response.
Some slang may be used, such as "Running Hot", or "Running Cold".
Some departments may use the terms "upgrade" and "downgrade" as well. If a unit is responding to a call without lights or sirens (code 1), and the unit later needs to turn on lights and sirens (code 3), the term upgrade may be used. The term downgrade may be used in the opposite situation.
A similar variation is to "reduce" or "increase code." For example, if there is a code 3 response to a situation, but the first units on scene have sufficient control of the situation, they may announce over the radio that responding units may "reduce code." In this example, to "reduce code" would mean to continue responding, but at code 2, rather than discontinue altogether; to alert units to discontinue altogether—e.g., because the suspect is in custody or there are already enough officers on scene—they would likely say they are "code 4."
Some paramedic/emergency medical service (EMS) agencies use Priority terms:
Possible shift to plain language.
In the U.S. the National Incident Management System (NIMS) states "it is required that plain language be used for multi-agency, multi-jurisdiction and multi-discipline events, such as major disasters and exercises" and federal grants became contingent on this beginning fiscal year 2006. NIMS also strongly encourages the use of plain language for internal use within a single agency.
United Kingdom.
The use of lights and sirens is up to the individual police officer driving to the call. The nature of the call is an aggravating factor when deciding when to use them. Calls are graded by either the control room direct (in the case of emergency calls) or by some sort of first contact centre (nonemergency calls). Grading is affected by such factors as the use or threat of violence at the incident being reported. Even though the grading is done by the control room, officers can request an incident be upgraded if they feel in their judgement they are needed immediately. They can also request to downgrade an incident if they feel they cannot justify using emergency equipment like blue lights and sirens.
Another variant in use within the UK.
A numerical grading system is used in some forces.
Ambulance responses in the UK are as follows. Some ambulance services allow driver discretion for Category 3/4 calls; this may be dependent on the type of call or how long it has been waiting for a response for. 999 calls to the ambulance service are triaged using either the NHS Pathways system or the Medical Priority Dispatch System.
The use of flashing lights and sirens is colloquially known as "blues and twos" which refers to the blue lights and the two-tone siren once commonplace (although most sirens now use a range of tones). In the UK, only blue lights are used to denote emergency vehicles (although other colours may also be used as sidelights, stop indicators, etc.). A call-out requiring the use of lights and sirens is often colloquially known as a "blue light run".
Australia.
Victoria.
Ambulance Victoria The information provided to Ambulance Victoria at the time of the triple zero call generates a case type and ambulance response code depending on the severity of the emergency.
There are three types of ambulance response:
Code 1: A time critical case with a lights and sirens ambulance response. An example is a cardiac arrest or serious traffic accident.
Code 2: An acute but non-time critical response. The ambulance does not use lights and sirens to respond. An example of this response code is a broken leg.
Code 3: A non-urgent routine case. These include cases such as a person with ongoing back pain but no recent injury.
Source: https://web.archive.org/web/20140125194345/http://www.ambulance.vic.gov.au/About-Us/How-we-work/In-a-Medical-Emergency/Response-Codes.html
Please note additional codes are used, but these are for internal purpose.
Country Fire Authority
There are two types of response for the Country Fire Authority which cover the outer Melbourne Area. These are similar to those used by Ambulance Victoria, minus the use of Code 2.
Code 1: A time critical event with response requiring lights and siren. This usually is a known and going fire or a rescue incident.
Code 2: Unused within the Country Fire Authority
Code 3: Non-urgent event, such as a previously extinguished fire or community service cases (such as animal rescue or changing of smoke alarm batteries for the elderly).
New South Wales.
Marine Rescue NSW
Code 1 Urgent Response - Use warning devices
Code 2 Semi Urgent Response - Use of Warning devices at skippers discretion
Code 3 Non Urgent Response - Warning Devices not needed
Code 4 Training - No Warning devices to be used unless specifically needed for training
The New South Wales Rural Fire Service and the New South Wales State Emergency Service use two levels of response, depending on what the call-out is and what has been directed of the crew attending the incident by orders of the duty officer:
The New South Wales Police Force uses two distinct classifications for responding to incidents. In order to respond 'code red' a driver must be suitably trained and have qualified in appropriate police driver training courses.
South Australia.
SA Ambulance Service use a Priority system.
Note: Priorities 0 and 3 have been reserved for future use. Priority 9 is used for administration taskings.
The South Australian Metropolitan Fire Service, Country Fire Service and South Australian State Emergency Service use a Priority System which has been recently updated.
All calls are routed through the Metropolitan Fire Service (Call Sign "Adelaide Fire") including State Emergency Service 132 500 calls.
During significant weather events the State Communication Centre (SCC) unit of the SES take over call taking responsibly. This operations centre is manned by volunteers routing calls for assistance to the closest unit who will dispatch the events to individual teams.
Queensland.
Queensland Police uses the priority system:
For Queensland Police code 1 and code 2 are exactly the same response time. Rarely will a job be given a priority code 1, instead officers will (in most cases) be told to respond code 2.
Northern Territory.
St John Ambulance Northern Territory uses terms to determine the response:
Western Australia.
St John Ambulance Western Australia uses the following codes to determine a response:
The Western Australian Police uses the following codes from 1 to 7 to determine response actions:
The Department of Fire and Emergency Services have two response codes: