Voice procedure includes various techniques used to clarify, simplify, and standardize spoken communications over two-way radios, in use by the military, in civil aviation, police and fire dispatching systems, citizens' band radio (CB), etc.
Voice procedure communications are intended to maximize clarity of spoken communication and reduce misunderstanding. It consists of signalling protocol such as the use of abbreviated codes like the CB radio ten-code, Q codes in amateur radio and aviation, police codes, etc., and jargon. For instance the United States Air Force uses a term "Check Rog" it means received and acknowledged and the United States Army uses the term "Hooah" which means the same thing.
Some elements of voice procedure are understood across many applications, but significant variations exist. The military of the NATO countries have similar procedures in order to make cooperation easier, and pseudo-military organizations often base their procedures on them, so some commonality exists there.
Words in voice procedure 
Some words with specialized meanings are used in radio communication throughout the English-speaking world, and in international radio communication, where English is the lingua franca.
- Affirmative — Yes (In aviation it is Affirm in order not to be confused with negative if only the last part of the tranmission is heard.)
- Negative — No
- Reading you Five / Loud and clear — I understand what you say; 5×5.
- Over — I have finished talking and I am listening for your reply. Short for "Over to you."
- Come in — You may begin speaking now
- Out — I have finished talking to you and do not expect a reply.
- Wait — I do not have the answer or information to hand, I will attempt to source the answer or information requested shortly but until then I have finished talking and do not expect a reply.
- Roger — (also roger that) I understand what you said; ok; all right [In aviation it is different: Roger = I have received all of your last transmission. It should not be used to answer a question requiring a yes or a no answer. Wilco = I have received your message, understand it, and will comply with it.]
- Ten four — I understand; ok; all right
- Copy — I heard what you just said; ok; all right.
- Wilco — Will comply (after receiving new directions).
- Go ahead or Send your traffic — Send your transmission.
- Say again repeat; Please repeat your last message (Repeat is only used in Canadian/US military radio terminology to request additional artillery fire)
- Break — Signals a pause during a long transmission to open the channel for other transmissions, especially for allowing any potential emergency traffic to get through. (Not used in British Army)
- Roger So Far — Confirm you have received and understood the contents of my transmission so far. This is used during Long Message Procedure (Messages lasting over 20 seconds prefixed by the Pro-Word 'Long Message' and the initiating C/S must give a gap of five seconds after the receiving station has replied with 'Roger'. This five seconds is to allow other Stations onto the net if they have important messages.
- Break-Break — Signals to all listeners on the frequency, the message to follow is priority. Almost always reserved for emergency traffic or in NATO forces, an urgent 9 line or Frag-O.
- Standby or Wait out — Pause for the next transmission. This does not usually entail staying off the air until the operator returns as they have used the word 'Out' which indicates the transmission has ended. The net is now free for other traffic to flow but users should be aware that the previous C/S may re-initiate a Call as per their 'Wait out'
- Callsign-Actual — Sometimes an individual (generally a superior) may have a person monitor the network for them. Saying "actual" after their callsign asserts you wish to speak to the specific person the callsign is attached to.
- Sécurité — Maritime safety call. Repeated three times. Has priority over routine calls.
- Pan-pan — Maritime/aviation urgency call. Repeated three times. Has priority over safety calls.
- Mayday — Maritime/aviation distress call. Repeated three times and at beginning of every following transmission relating to the current distress situation. Has priority over urgency and safety calls.
"Roger" was the U.S. military designation for the letter R (as in received) from 1927 to 1957.
Example usage 
The Federal Aviation Administration uses the term phraseology to describe voice procedure or communications protocols used over telecommunications circuits. An example is air traffic control radio communications. Standardized wording is used and the person receiving the message may repeat critical parts of the message back to the sender. This is especially true of safety-critical messages. Consider this example of an exchange between a controller and an aircraft:
Aircraft: Boston Tower, Warrior tree fife foxtrot (35F), holding short of two two right.
Tower: Warrior Tree fife foxtrot, Boston Tower, runway two two right, cleared for immediate takeoff.
Aircraft: Roger, tree fife foxtrot, cleared for immediate takeoff, two two right.
On telecommunications circuits, disambiguation is a critical function of voice procedure. Due to any number of variables, including radio static, a busy or loud environment, or similarity in the phonetics of different words, a critical piece of information can be misheard or misunderstood; for instance, a pilot being ordered to eleven thousand as opposed to seven thousand. To reduce ambiguity, critical information may be broken down and read as separate letters and numbers. To avoid error or misunderstanding, pilots will often read back altitudes in the tens of thousands using both separate numbers and the single word (example: given a climb to 10,000 ft, the pilot replies "[Callsign] climbing to One zero, Ten Thousand"). However, this is usually only used to differentiate between 10,000 and 11,000 ft since these are the most common altitude deviations. The runway number read visually as eighteen, when read over a voice circuit as part of an instruction, becomes one eight. In some cases a spelling alphabet is used (also called a radio alphabet or a phonetic alphabet) . Instead of the letters AB, the words Alpha Bravo are used. Main Street becomes Mike Alpha India November street, clearly separating it from Drain Street and Wayne Street. The numbers 5 and 9 are pronounced "fife" and "niner" respectively, since "five" and "nine" can sound the same over the radio.
Over fire service radios, phraseology may include words that indicate the priority of a message, for example:
Forty Four Truck to the Bronx, Urgent!
San Diego, Engine Forty, Emergency traffic!
Words may be repeated to modify them from traditional use in order to describe a critical message:
Evacuate! Evacuate! Evacuate!
Police Radios[where?] also use this technique to escalate a call that is quickly becoming an emergency.
Code 3! Code 3! Code 3!
Railroads have similar processes. When instructions are read to a locomotive engineer, they are preceded by the train or locomotive number, direction of travel, and the engineer's name. This reduces the possibility that a set of instructions will be acted on by the wrong locomotive engineer:
Five Sixty Six West, Engineer Jones, okay to proceed two blocks west to Ravendale.
Phraseology on telecommunications circuits may employ special phrases like ten codes, Sigalert, Quick Alert! or road service towing abbreviations such as T6. This jargon may abbreviate critical data and alert listeners by identifying the priority of a message. It may also reduce errors caused by ambiguities involving rhyming, or similar-sounding, words.
Maritime procedure 
(Done on VHF Ch 16)
Boat "Albacore" talking to Boat "Bronwyn"
Albacore: Bronwyn, Bronwyn, Bronwyn* this is Albacore, over. (*3×1 is very amateur sounding: A 1×1 (i.e. 'Bronwyn this is Albacore'), or 2×2 is a proper call-up. 3×3 is only used in adverse atmospheric conditions, when communications are particularly bad.
Bronwyn: Albacore, this is Bronwyn, over. (** At this point switch to a working channel as 16 is for distress and hailing only**)
Albacore: This is Albacore. Want a tow and are you OK for tea at Osbourne Bay? over.
Bronwyn: This is Bronwyn. Negative, got engine running, 1600 at clubhouse fine with us. over.
Albacore: This is Albacore, Roger, out.
"Copy that" is incorrect. COPY is used when a message has been intercepted by another station, i.e. a third station would respond:
Nonesuch: Brownwyn, this is Nonesuch. Copied your previous, will also see you there, out.
One should always use one's own callsign when transmitting.
This system works better when the message rate and signal quality is low.
British Army 
Station C21 (charlie-two-one Alpha) talking to C33 (charlie-three-three Bravo):
C21A: Hello C33B, this is C21A, over.
C33B: C33B, send, over.
C21A: Have you got C1ØD Sunray at your location?, over.
C33B: No, I think he is with C3ØC, over.
C21A: Roger, out.
The advantage of this sequence is that the recipient always knows who sent the message.
The downside is that the listener only knows the intended recipient from the context of the conversation. Requires moderate signal quality for the radio operator to keep track of the conversations.
However a broadcast message and response is fairly efficient.
Ø: Hello all call signs, this is Ø. Radio check, over.
1: 1. ok. over.
2: 2. ok. over.
3: 3. difficult. over.
4: 4. ok. over.
Ø: Ø. Okay, out.
The difficult response is to tell Ø that the radio signal is not good but will work. Ø can now re-initiate a Call onto 3 and start another R/C or instruct them to relocate, change settings, etc.
So it could carry on with:
4: 4. ok. over.
Ø: Ø. Okay, out to you. Hello 3 this is Ø, move 100m North and initiate Radio Check once in position, over.
3: 3. Wilco, out.
Frequency control 
In public radio, voice procedure controls the behavior and use of the frequency between each operator. Deregulated frequencies, such as Family Radio Service has no voice procedure, but due to the limited range of transmission it is unlikely a transmission will be heard outside of a single party. On signals open to the public with broader reception, such as citizens band, there is only enough protocol to allow operators to speak one at a time or allow emergency traffic to go through. Otherwise, there is no prioritization or rules to the communication outside of following local and federal laws regarding communication. Other stations requiring licensure such as amateur radio bands or MARS users (which includes civilian amateur radio operators) have strict usage and transmission rules which operators are trained on (as part of their licensing process) that allows authorized users to communicate. Regulated Radio frequencies often have unlicensed users who are unaware of the protocol on a certain channel and are asked to sign off if they fail to identify a callsign as a licensed operator, or are reported by licensed operators to the licensing body for possible advisement or citation. Amateur radio frequencies also may have assigned functions which may allow or disallow certain traffic including voice, such as continuous wave (see Morse code) transmission or data-only transmission frequencies.
Structured use is seen in voice procedure for government, military and disaster command usage. In law enforcement and public safety use, voice procedure follows a protocol that governs who can speak on a frequency and when. Since modern police frequencies are on a restricted bandwidth it is unlikely that an unlicensed party will interrupt communication; all operators on a frequency are assumed to be authorized to utilize a channel unless proven otherwise. Licensed radios in law enforcement often utilize trunking, or multiple frequencies selected by a control tower at random which prevents single-channel scanners from picking up a transmission. A frequency may be dispatch controlled (or controlled net) which is controlled by one control station and any parties wishing to use the frequency must direct all calls to the control station who routes calls as needed to necessary parties. A tactical frequency (or tactical net) has no control station, and is intended to be used on an ad-hoc basis for situations, such as multiple units attempting an arrest who surround a single property. Tactical frequencies may or may not be trunked and may be susceptible to single-channel scanner reception.
See also 
- Five by five
- ICAO spelling alphabet
- List of international common standards
- Procedure word
- Station identification
- FAA (2012-07-26). "Federal Aviation Administration Pilot/Controller Glossary". FAA.
- SDSTAFF Robin; Straight Dope Science Advisory Board (2007-02-27). "Why do pilots say "roger" on the radio?". The Straight Dope. Archived from the original on 2008-01-29.
- See: "Section 2: Radio Communications Phraseology and Techniques," Aeronautical Information Manual, US Department of Transportation, Federal Aviation Administration. Any year AIM will serve as an example. Another example is "Completing the Loop: Two-Way Communication," Special Report: Improving Firefighter Communications, USFA-TR-099/January 1999, (Emmitsburg, Maryland: U.S. Fire Administration, 1999) pp. 27.
- See, "Problem Reporting," Special Report: Improving Firefighter Communications, USFA-TR-099/January 1999, (Emmitsburg, Maryland: U.S. Fire Administration, 1999) pp. 25-26. FDNY has implemented these ideas and they were observed on publicly released FDNY 9-11-01 logging recorder audio CDs. Portions of these CDs were broadcast on news programs.
- For an example of fire procedures, look at "Communications Procedures," XII-A-4.JH.970314, (Los Gatos, California, Santa Clara County Fire Department, Training Division, 03/14/1997).