View source for Citizens band radio

{{short description|Land mobile radio system}}
[[Image:CB Base Station.jpg|thumb|right|Typical 1980s CB radio intended for use at a fixed location and used with outdoor antenna. "Base stations" are usually operated on household [[AC power]] but can also be used from a vehicle's [[Direct current|DC power]] system if operated in a vehicle or from an emergency battery source. Shown with Astatic brand D-104 desk mic|alt=Black-and-gray 1980s-era base station, with tall round desk microphone]]
[[Image:Citizens Band CB Cobra 18 WX ST II with microphone.jpeg|thumb|Cobra 18&nbsp;WX&nbsp;ST II mobile CB radio with microphone|alt=Small black mobile radio with hand-held microphone and long, coiled mic cord]]
[[File:Cobra Handheld CB Radio.jpg|thumb|Cobra 50 WX ST Handheld CB Radio]]

'''Citizens band radio''' ('''CB radio''') is a [[land mobile radio system]], a system allowing short-distance one-to-many bidirectional voice communication among individuals, using [[two-way radio]]s operating near 27 [[Hertz|MHz]] (or the 11-m wavelength) in the [[high frequency]] or [[shortwave]] band. Citizens band is distinct from other [[personal radio service]] allocations such as [[Family Radio Service|FRS]], [[General Mobile Radio Service|GMRS]], [[Multi-Use Radio Service|MURS]], [[UHF CB]] and the [[Amateur Radio|Amateur Radio Service]] ([[amateur radio operator|"ham"]] radio). In many countries, CB operation does not require a license and may be used for business or personal communications.

Like many other land mobile radio services, multiple radios in a local area share a single frequency channel, but only one can transmit at a time. The radio is normally in receive mode to receive transmissions of other radios on the channel; when users want to communicate they press a "[[push to talk]]" button on their radio, which turns on their transmitter. Users on a channel must take turns transmitting. In the [[United States|US]] and [[Canada]], and in the [[European Union|EU]] and the [[United Kingdom|UK]], transmitter power is limited to 4&nbsp;[[watt]]s when using [[Amplitude modulation|AM]] and [[Frequency modulation|FM]] and 12 W [[Peak envelope power|PEP]] when using [[Single-sideband modulation|SSB]]. Illegal amplifiers to increase range are common.{{citation needed|date=May 2024}}

CB radios using an omni-directional vertical antenna typically have a range of about 5&nbsp;km to 30&nbsp;km depending on terrain, for line of sight communication; however, various radio propagation conditions may intermittently allow communication over much greater distances. Base stations however may be connected to a directional [[Yagi-Uda|Yagi–Uda antenna]] commonly called a Beam or a Yagi.

Multiple countries have created similar radio services, with varying technical standards and requirements for licensing. While they may be known by other names, such as the General Radio Service in Canada,<ref>{{cite web |url=http://strategis.ic.gc.ca/epic/site/smt-gst.nsf/en/sf01016e.html |title=RIC-18 — General Radio Service (GRS) |first=Government of Canada, Innovation, Science and Economic Development Canada, Office of the Deputy Minister, Spectrum, Information Technologies and|last=Telecommunications |website=strategis.ic.gc.ca |date=27 August 2002 |access-date=8 May 2018 |url-status=live |archive-url=https://web.archive.org/web/20080112203042/http://strategis.ic.gc.ca/epic/site/smt-gst.nsf/en/sf01016e.html |archive-date=12 January 2008}}</ref> they often use similar frequencies (26–28&nbsp;MHz) and have similar uses, and similar technical standards. Although licenses may be required, eligibility is generally simple. Some countries also have personal radio services in the UHF band, such as the European [[PMR446]] and the Australian UHF CB.

==History==
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===United States===
{{Main|CB radio in the United States}}

====Origins====
[[File:QSL KHI-6261.jpg|thumb|right|A QSL card issued by a US CB station in 1963]]

The citizens band radio service originated in the United States as one of several personal radio services regulated by the [[Federal Communications Commission]] (FCC). These services began in 1945 to permit citizens a radio band for personal communication (e.g., radio-controlled model airplanes and family and business communications). In 1948, the original CB radios were designed for operation on the 460–470&nbsp;MHz UHF band.<ref>{{cite web |url=https://www.retrocom.com/wtcollect/27_megacycle_history_in_the_u.htm |access-date=2010-02-10 |url-status=live |archive-url=https://web.archive.org/web/20101128232848/http://retrocom.com/wtcollect/27_megacycle_history_in_the_u.htm |archive-date=2010-11-28 |df=dmy-all |title=27&nbsp;Megacycle History}}</ref> There were two classes of CB radio: "A" and "B". Class&nbsp;B radios had simpler technical requirements, and were limited to a smaller frequency range. [[Alfred J. Gross|Al Gross]] established the Citizens Radio Corporation during the late 1940s to manufacture class&nbsp;B handhelds for the general public.<ref name=Kneitel1988/>{{rp|13}} Originally designed for use by the public sector, the Citizens Radio Corporation sold over 100,000 units, primarily to farmers and the US Coast Guard.<ref>{{Cite web|date=2020-06-25|title=Citizen Band (CB) Radio|url=https://www.nowiresradio.com/citizen-band-radio/|access-date=2020-07-06|website=No Wires Radio|language=en-US}}</ref>

[[Ultra-high frequency]] (UHF) radios, at the time, were neither practical nor affordable for the average consumer. On September 11, 1958<ref name=Kneitel1988/>{{rp|14}} CB service class&nbsp;D was created on 27&nbsp;MHz, and this band became what is commonly known today as "Citizens Band". Only 23&nbsp;channels were available at the time; the first 22 were taken from the former [[amateur radio service]] 11-meter band, and channel&nbsp;23 was shared with radio-controlled devices. Some hobbyists continue to use the designation "11&nbsp;meters" to refer to the Citizens Band and adjoining frequencies. Part&nbsp;95 of the Code of Federal Regulations regulates the class&nbsp;D CB service, on the 27&nbsp;MHz band, since the 1970s and continuing today.<ref>{{cite web |url=http://apps.fcc.gov/eas/comments/GetPublishedDocument.html?id=135&tn=472290 |archive-url=https://web.archive.org/web/20210324164806/https://apps.fcc.gov/eas/comments/GetPublishedDocument.html?id=135&tn=472290 |url-status=dead |archive-date=2021-03-24 |series=FCC Part&nbsp;95 |title=Overview |access-date=2011-10-21 |df=dmy-all}}</ref> Most of the 460–470&nbsp;MHz band was reassigned for business and public-safety use; CB Class&nbsp;A is the forerunner of the [[General Mobile Radio Service]] (GMRS). CB Class&nbsp;B is a more distant ancestor of the [[Family Radio Service]]. The [[Multi-Use Radio Service]] is another two-way radio service in the [[Band III|VHF high band]]. An unsuccessful petition was filed in 1973 to create a CB Class&nbsp;E service at 220&nbsp;MHz, (part of the amateur radio [[1.25-meter band]] at the time) which was opposed by amateur radio organizations and others.<ref>{{cite news |first=Peter M. |last=Hurd |title=Amateur Radio and MARS News |magazine=Signal |date=May–June 1978 |page=112}}</ref> There are several other classes of personal radio services for specialized purposes (such as [[remote control]] devices).

During the 1960s, the service was used by small businesses (e.g., electricians, plumbers, carpenters), [[truck driver]]s and radio hobbyists. By the late 1960s, advances in [[solid state (electronics)|solid-state]] electronics allowed the weight, size, and cost of the radios to fall, giving the public access to a communications medium previously only available to specialists.<ref name="ind"/> CB clubs were formed; a [[CB slang]] language evolved alongside [[ten-code]], similar to those used in [[emergency service]]s.

==== {{anchor|Growing popularity in the 1970s|Use in popular culture|Famous users}}1970s popularity ====
After the [[1973 oil crisis]], the U.S. government imposed a [[National Maximum Speed Law|nationwide 55 mph speed limit]], and fuel shortages and rationing were widespread. Drivers (especially commercial [[truck driver|truckers]]) used CB radios to locate service stations with better supplies of fuel, to notify other drivers of [[speed trap]]s, and to organize blockades and convoys in a 1974 strike protesting the new speed limit and other trucking regulations.<ref>{{cite web |url=https://news.google.com/newspapers?nid=1893&dat=19750216&id=qm0fAAAAIBAJ&sjid=ZtUEAAAAIBAJ&pg=841,5104091&hl=en |title=The Southeast Missourian |via=Google News Archive Search |website=news.google.com |access-date=8 May 2018}}</ref> The radios were crucial for independent truckers; many were paid by the mile, and the 55&nbsp;mph speed limit lowered their productivity.<ref name="ind">{{cite magazine |publisher=[[The Independent Institute]] |magazine=Independent Review |year=2011 |volume=15 |issue=3 |title="I can't drive 55": The economics of the CB radio phenomenon}}</ref>

Their use spread further into the general population in the US in the middle of the 1970s. Originally, CB radios required the use of a [[callsign (radio)|callsign]] in addition to a purchased license ($20 in the early 1970s, reduced to $4 on March 1, 1975, or ${{Formatnum:{{Inflation|US|4|r=1|1975}}}} in {{Inflation-year|US}} dollars). However, when the CB craze was at its peak, many people ignored the requirement and invented their own nicknames (known as "handles"). Lax enforcement of the rules on authorized use of CB radio led to further widespread disregard of regulations (such as for [[antenna (radio)|antenna]] height, distance communications, licensing, call signs, and transmitter power). Individual licensing came to an end on April 28, 1983.<ref>{{cite news |url=https://www.nytimes.com/1983/04/28/us/fading-cb-craze-signals-end-to-licensing.html |title=Fading CB craze signals end to licensing |first=Ernest |last=Holsendolph <!-- Special to the New York Times --> |newspaper=[[The New York Times]] |at=Section&nbsp;A, page&nbsp;19 |date=April 28, 1983}}</ref>

The growing popularity of CB radios in the 1970s was frequently depicted in film, television, music and books. Movies such as ''[[Smokey and the Bandit]]'' (1977), ''[[Breaker! Breaker!]]'' (1977), ''[[Handle with Care (1977 film)|Handle with Care]]'' (also released as ''Citizens Band''; 1977), and [[Convoy (1978 film)|''Convoy'']] (1978), made heavy reference to the phenomenon, as did television series such as [[Movin' On (TV series)|''Movin' On'']] (debuted in 1974), ''[[The Dukes of Hazzard]]'' (debuted in 1979) and the animated series ''[[CB Bears]]'' (debuted in 1977) helped cement CB radio's status as a nationwide craze in the United States over the mid- to late-1970s. In [[Stephen King]]'s 1978 novel ''[[The Stand]]'', Ralph Brentner's radio signal from [[Boulder, Colorado]] was able to be received over CB.<ref name="TheStandComplete">{{cite book |last=King |first=Stephen |author-link=Stephen King |title=The Stand |date=2012 |publisher=Anchor Books |location=New York |isbn=978-0-385-52885-6 |edition=First Anchor Books Edition; "Complete and uncut edition"}}</ref> The phenomenon also inspired several country and rock music songs in 1975 and 1976.

* [[C. W. McCall]]'s [[novelty song]] "[[Convoy (song)|Convoy]]" (1975) climbed to #1 on the [[Billboard (magazine)|''Billboard'']] [[Billboard Hot 100|Hot 100]] in January&nbsp;1976 and to #2 on the [[UK singles chart]] during the spring of 1976. The song inspired the 1978 [[Convoy (1978 film)|film of the same name]] directed by [[Sam Peckinpah]]. In the UK, [[BBC Radio One]] DJs [[Dave Lee Travis]] and [[Paul Burnett]] covered the song with altered lyrics, released as "Convoy GB" under the moniker ''Laurie Lingo & the Dipsticks''. The cover peaked at #4 on the UK chart in the spring of 1976. McCall also recorded "[['Round the World with the Rubber Duck]]", a sequel to "Convoy". It was released in the late spring of 1976 and peaked at #1 on the ''Billboard'' [[Bubbling Under Hot 100]] chart.
* [[Dave Dudley]]'s 1975 novelty country song "Me and ol' CB" peaked at #12 on the ''Billboard'' [[Hot Country Songs]] chart and at #8 on the Canadian country chart.
* [[The White Knight (Cledus Maggard song)|"The White Knight"]], a novelty [[country music]] song, was written by [[Jay Huguely]], who – recording as ''Cledus Maggard & The Citizen's Band'' – enjoyed a brief run of national popularity with the song when it became a hit in 1976, peaking at #19 on the ''Billboard'' Hot 100.<ref>[https://www.legacy.com/obituaries/latimes/obituary.aspx?n=james-wesley-huguely&pid=126585591 James Wesley Huguely=Cledus Maggard] Retrieved 9 February 2021</ref>
* "[[One Piece At A Time]]" by [[Johnny Cash]] peaked at #12 on the UK charts in the early summer of 1976.
* The lyrics to [[The Outlaws (band)|the Outlaws]]'s country rock song "[[Breaker-Breaker]]" capitalize on the fad. The record peaked at #94 on the ''Billboard'' Hot 100 in the spring of 1976.
* [[Teddy Bear (Red Sovine song)|"Teddy Bear"]] by country singer [[Red Sovine]] charted at #6 in the UK in the late summer of 1976.
* Country singer [[Rod Hart]]'s "C.B. Savage" is a gay-themed country novelty song about truckers plagued by a mysterious effeminate CB aficionado.<ref>{{cite news |title=Gay ballad is joined by "Savage" |url=https://books.google.com/books?id=ryQEAAAAMBAJ&dq=%22Rod+hart%22+%22cb+savage%22&pg=PT52 |access-date=11 October 2023 |publisher=Billboard |date=September 13, 1976}}</ref><ref>{{cite web |last1=Adams |first1=Greg |title=Rod Hart - Breakeroo! |url=https://www.allmusic.com/album/breakeroo%21-mw0000880699 |website=Allmusic |access-date=11 October 2023}}</ref>
[[File:Citizens Radio License 1972.jpg|thumb|Image of Citizens Radio license 1972 issued by the United States Federal Communications Commission]]

[[Betty Ford]], the former [[First Lady of the United States]], used the CB handle "First Mama".<ref>{{cite news |author=Tweed, Michael |url=https://www.nytimes.com/2006/12/31/us/31betty.html |title=Back in view, a First Lady with her own legacy |archive-url=https://web.archive.org/web/20161216222605/http://www.nytimes.com/2006/12/31/us/31betty.html |archive-date=2016-12-16 |newspaper=[[The New York Times]] |date=31 December 2006}}</ref>

Voice actor [[Mel Blanc]] was also an active CB operator, often using "[[Bugs Bunny|Bugs]]" or "[[Daffy Duck|Daffy]]" as his handle and talking on the air in the [[Los Angeles]] area in one of his many voice characters. He appeared in an interview (with clips having fun talking to children on his home CB radio station) in the ''NBC Knowledge'' television episode about CB radio in 1978. Similar to Internet [[chat room]]s a quarter-century later, CB allowed people to get to know one another in a quasi-anonymous manner.

Originally, the U.S. had 23&nbsp;CB channels; the 40&nbsp;channel band plan was implemented in 1977. Two more channels between 22 & 23, commonly referred to as 22A & 22B, were available. Several people had 22A, but few had 22B. In the early 1970s Radio Shack sold a "base station" CB radio that contained a crystal for each of the 23&nbsp;channels, two extra slots existed, and one could order the 22A & 22B crystals for an easy plug-in. Channel&nbsp;9 was officially reserved for emergency use by the FCC in 1969.<ref name=Chiltons1977/>{{rp|12}} Channel&nbsp;10 was originally often used for highway travel communications east of the [[Mississippi River]], and channel&nbsp;19 west of the Mississippi; channel&nbsp;19 then became the preferred highway channel in most areas, as it did not have [[adjacent-channel interference]] problems with channel&nbsp;9. Many CBers called channel&nbsp;19 "the trucker's channel". The FCC originally restricted channel&nbsp;11 for use as the calling channel.

The original FCC output power limitation for CB radios was "5&nbsp;watts DC input to the final amplifier stage", which was a reference to the earlier radios equipped with tubes.  With solid state radios becoming more common in the 1970s, the FCC revised this specification at the same time the authorized channels were increased to 40. The current specification is simply "4&nbsp;watts output (AM) or 12&nbsp;watts output (SSB)" as measured at the antenna connector on the back of the radio. The old specification was often used in false advertising by some manufacturers who would claim their CB radios had "5&nbsp;watts" long after the specification had changed to 4&nbsp;watts output. The older 23&nbsp;channel radios built under the old specifications typically had an output of around 3.5 to 3.8&nbsp;watts output when measured at the antenna connector. The FCC simply rounded up the old "5&nbsp;watts DC input to the final amplifier stage" specification to the new "4&nbsp;watts output as measured at the antenna connector on the back of the radio", resulting in a far simpler and easier specification.

Initially, the FCC intended for CB to be the "poor man's business-band radio", and CB regulations were structured similarly to those regulating the [[business band]] radio service. Until 1975,<ref name=Chiltons1977/>{{rp|14}} only channels&nbsp;9–14 and 23{{efn|Channels&nbsp;10–14 and 23, after channel&nbsp;9 was reserved for emergency use.}} could be used for "interstation" calls (to other licensees). Channels&nbsp;1–8 and 15–22 were reserved for "intrastation" communications (among units with the same license).{{efn|The terms "interstation" and "intrastation" appear in the FCC's Part&nbsp;95 rules from that time period.}} After the inter-station/intra-station rule was dropped, channel&nbsp;11 was reserved as a calling frequency (for the purpose of establishing communications); however, this was withdrawn in 1977.<ref name=Chiltons1977/>{{rp|120}} During this early period, many CB radios had "inter-station" channels colored on their dials, while the other channels were clear or normally colored.{{efn|except channel&nbsp;9, which was usually colored red.}} It was common for a town to adopt an inter-station channel as its "home" channel. This helped prevent overcrowding on channel&nbsp;11, enabling a CBer to monitor a town's home channel to contact another CBer from that town instead of a making a general call on channel&nbsp;11.

====Boating and the U.S. Coast Guard====
Since the price of CB was dropping and [[Marine VHF radio|VHF Marine Band]] was still expensive, many boaters installed CB radios. Business caught on to this market, and introduced marine CBs containing a weather band (WX). There was much controversy over whether the Coast Guard should monitor CB radio, but for safety they did so, using [[Motorola]] base stations at their search and rescue stations. The Coast Guard stopped this practice in the late 1980s and recommends VHF Marine Band radios for boaters.<ref>{{cite web |title=Radio Information for Boaters |url=http://www.navcen.uscg.gov/?pageName=mtBoater |publisher=United States Coast Guard |url-status=live |archive-url=https://web.archive.org/web/20110614020205/http://www.navcen.uscg.gov/?pageName=mtBoater |archive-date=2011-06-14 |df=dmy-all}}</ref>

===={{anchor|Present day usage}}21st-century use====
CB has lost much of its original appeal due to development of [[mobile phone]]s, the [[internet]] and the [[Family Radio Service]]. Changing [[radio propagation]] for long-distance communications due to the 11&ndash;year [[sunspot cycle]] is a factor at these frequencies. In addition, CB may have become a victim of its own popularity; with millions of users on a finite number of frequencies during the mid-to-late 1970s and early 1980s, channels often were noisy and communication difficult, which reduced interest among hobbyists. Business users (such as tow-truck operators, plumbers, and electricians) moved to the VHF and UHF business band frequencies. The business band requires an FCC license, and usually results in an assignment to a single frequency. The advantages of fewer users sharing a frequency, greater authorized output power, clarity of [[Frequency modulation|FM]] transmission, lack of interference by distant stations due to [[Skywave|skip propagation]], and consistent communications made the VHF ([[Very high frequency|Very High Frequency]]) radio an attractive alternative to the overcrowded CB channels.

With these factors in play, CB radio has once again gained popularity in recent years, an uptick not seen since the '90s. Manufacturers report an increase in sales, while social media sites like YouTube show a growing popularity in CB radio content, mainly as a hobby. The technology has also given way to more compact CB radios with far more features afforded in older models.  {{citation needed|date=March 2023}}

The FCC restricts channel&nbsp;9 to emergency communications and roadside assistance.<ref>{{cite web |url=http://www.fcc.gov/encyclopedia/citizens-band-cb-service |title=Citizens Band Radio Service (CBRS) |date=4 August 2011 |website=fcc.gov |access-date=8 May 2018 |url-status=live |archive-url=https://web.archive.org/web/20151204202207/https://www.fcc.gov/encyclopedia/citizens-band-cb-service |archive-date=4 December 2015}}</ref> Most highway travelers monitor channel&nbsp;19. Truck drivers still use CB, which is an effective means of obtaining information about road construction, accidents and [[Speed limit enforcement|police speed traps]].

===Australia===
{| class="wikitable floatright" style="width: 20em;"
|+27&nbsp;MHz CB channels for use in Australia
|-
! Channel Number !! Frequency (MHz) !! Purpose
|-
| 8 || 27.055 || Highway Channel
|-
| 9 || 27.065 || Emergency Channel
|-
| 11 || 27.085 || AM Call Channel
|-
| 16 || 27.155 || LSB Call Local
|-
| 35 || 27.355 || LSB Call DX
|}
{| class="wikitable floatright" style="width: 20em;"
|+ List of 27&nbsp;MHz Marine Radio channels for use in Australia<ref name="MSV" />
|-
! Channel Number !! Frequency (MHz) !! Purpose
|-
| 88             || 27.88           || Distress, urgency, safety and calling (primary)
|-
| 86             || 27.86           || Distress, urgency, safety and calling (secondary)
|-
| 68             || 27.68           || Commercial operations (ship–shore, ship–ship)
|-
| 90             || 27.9            || Non-commercial operations (ship–shore)
|-
| 91             || 27.91           || Non-commercial operations (ship–shore)
|-
| 94             || 27.94           || Specific events only (ship–shore, ship–ship)
|-
| 96             || 27.96           || Non-commercial operations (ship–ship)
|-
| 98             || 27.98           || Safety and rescue operations (ship–shore, ship–ship)
|-
| 72             || 27.72           || Commercial fishing operations (ship–shore, ship–ship)
|-
| 82             || 27.82           || Commercial fishing operations (ship–shore, ship–ship)
|}
[[File:2007-12-06 Hand-held citizens' band (CB) radio.jpg|thumb|left|upright=.5|Hand-held CB transceiver; antenna not shown|alt=Close-up of gray walkie-talkie CB radio, viewed from the side]]

Before CB was authorized in Australia, hand-held 27-MHz "walkie-talkies" were available, which used several frequencies between the present CB channels, such as 27.240&nbsp;MHz.<ref>{{cite web |url=http://users.bigpond.net.au/acrm/histpref.html |publisher=ACRM |title=CB Radio History |archive-url=https://web.archive.org/web/20060917214644/http://www.users.bigpond.net.au/acrm/histpref.html |archive-date=2006-09-17 |df=dmy-all}}</ref><ref>{{cite web |title=Radiocommunications (27&nbsp;MHz Handphone Stations) Class Licence 2015 |url=https://www.legislation.gov.au/Details/F2015L01441 |website=www.legislation.gov.au |publisher=Commonwealth of Australia |access-date=1 January 2019 |language=en}}</ref> By the mid-1970s, hobbyists were experimenting with handheld radios and unauthorized 23&nbsp;channel American CB radios. At that time in Australia, licensed ham operators and Emergency Services still used the 11 meter band<ref>{{cite web |url=http://users.bigpond.net.au/acrm/histmovt.html#1975 |publisher=ACRM |title=Movement |archive-url=https://web.archive.org/web/20060917215924/http://www.users.bigpond.net.au/acrm/histmovt.html |archive-date=2006-09-17 |df=dmy-all}}</ref> which was not yet available for CB use. Multiple CB clubs had formed by this time, which assigned call signs to members, exchanged [[QSL card]]s, and lobbied for the legalisation of CB. In late 1977, having legalised Australian CB and allowed the import / sale of American and Japanese 23&nbsp;channel sets, the Federal Government drafted new interim regulations for Australian 18&nbsp;channel transceivers. The new RB249 regulations came into effect on January 1, 1978, and the last official registration date for 23&nbsp;channel sets was January 31, 1978. After this date, use of unregistered 23&nbsp;channel CB sets was deemed illegal and unlicensed sets were no longer eligible to be licensed. The 18&nbsp;channel band plan used 16&nbsp;channels of the 23&nbsp;channel CB radios plus 2&nbsp;extra channels at 27.095 and 27.195&nbsp;MHz, to make up the 18&nbsp;channels. The original channels&nbsp;1, 2, 3, 4, 10, 21 and 23 were deleted from the 18&nbsp;channel band plan. So channel 1 on an 18 channel was actually channel&nbsp;5 on a 23&nbsp;channel radio. These roughly corresponded to the present channels&nbsp;5–22, except for the two unique frequencies that are known as 11A (Channel&nbsp;7 on an 18&nbsp;channel Australian CB) and 19A (Channel&nbsp;16 on an 18&nbsp;channel Australian CB) or remote control frequencies but are no longer part of the Australian 27&nbsp;MHz CB band since 40&nbsp;Channels were introduced.<ref>{{cite web |url=http://acbro.org/ozchannels.htm |publisher=ACBRO |title="Aussie" 18&nbsp;Channel Radio Guide |archive-url=https://web.archive.org/web/20040113190735/http://www.acbro.org/ozchannels.htm |archive-date=2004-01-13 |df=dmy-all}}</ref> On January 1, 1982, the American 40&nbsp;channel band plan was adopted.

From the outset, the government attempted to regulate CB radio with license fees and call signs, but eventually they abandoned this approach. Enthusiasts rushed for licences when the doors opened at post offices around Australia in mid-1977 and by the end of the first quarter of 1978 an estimated 200,000&nbsp;licences were issued (Australia's Population in 1978 was 14.36&nbsp;million). The regulations called for one licence per CB radio. The price for a licence in 1977 was AU$25&nbsp;per year (In mid 1977 the Australian Dollar exchange rate was AU$0.90 to US$1.00), a not insubstantial amount for the average Australian wage-earner. Australian CB radio uses AM, USB, and LSB modes (no FM) on 27&nbsp;MHz, allowed output power being 4&nbsp;Watts AM and 12&nbsp;Watts SSB. When [[UHF CB]] was first legalised the 27&nbsp;MHz CB Band was intended to be closed to Australian CBers in 1982 and only the 477&nbsp;MHz UHF band was to continue, however this did not eventuate. The first 477&nbsp;MHz CB radio in 1977 was designed and made in Australia by Philips TMC and was a 40&nbsp;channel CB called the FM320.

The first CB club in Australia was the ''Charlie Brown Touring Car Club'' (CBTCC),<ref>{{cite web |title=CB Radio History |url=https://www.acrm.org.au/history/hist_cb_radio.html |website=www.acrm.org.au |publisher=Australian Citizens Radio Monitors (South Australia) Incorporated |access-date=1 January 2019 }}</ref> which formed in [[Morwell, Victoria]] in 1967 and consisted mainly of [[four-wheel drive]] enthusiasts. The club used the prefix "GL" (for [[Gippsland]]), since "CB" could not be used.<ref>* GL 226 (VK3PJB) ex-Secretary GL Club, Australia{{full citation needed |date=November 2019}}</ref> After July 1, 1977, the club changed its name to Citizens Band Two Way Communication Club (CBTCC).{{Citation needed|date=September 2009}} Other early clubs were "LV" ([[Latrobe Valley]]) and "WB" (named after Wayne Britain). Members of these clubs are still active, and have also become [[amateur radio operator]]s. Other Australian cities which became CB radio "hotspots" were Seymour, Benalla, Holbrook and Gundagai, all located on the busy Hume Highway between Melbourne and Sydney. Other regional cities such as Bendigo, Mildura, Mount Gambier and Port Augusta, developed lively, colourful CB radio communities.

With the introduction of [[UHF CB]] radios in 1977, many operators used both UHF and HF radios and formed groups to own and operate local FM repeaters. Members of the CBTCC formed what became known as Australian Citizens Radio Movement (ACRM) in the early 1970s; this organization became the voice for legalization of CB radio throughout Australia. After peaking in the 1970s and early 1980s, the use of 27&nbsp;MHz CB in Australia has fallen dramatically due to the introduction of 477&nbsp;MHz UHF CB (with FM and repeaters) and the proliferation of cheap, compact handheld UHF transceivers. Technology such as mobile telephones and the internet have provided people with other choices for communications. The Australian government has changed the allocation of channels available for UHF CB Radio from 40 to 80, and doubled the number of repeater channels from 8 to 16.<ref>{{cite web |url=http://www.uhfcb.com.au |title=[no title cited] |archive-url=https://web.archive.org/web/20090508232930/http://www.uhfcb.com.au/ |archive-date=2009-05-08 |df=dmy-all}}</ref>

Several channels are allocated for maritime use in Australia. Australia also permits the use of [[marine VHF radio]]. 27&nbsp;MHz radios have the advantage of not requiring a certificate of proficiency to use,<ref>{{cite web |title=Marine radio qualifications |url=https://www.acma.gov.au/Citizen/TV-Radio/Radio/Marine-and-Amateur-Radio/marine-radio-qualifications |website=www.acma.gov.au |publisher=Australian Communications and Media Authority |access-date=1 January 2019 |language=en |date=17 September 2018}}</ref> however they may not be monitored by rescue organisations or larger vessels. VHF radios are recommended by state agencies, such as Marine Safety Victoria and [[Marine Rescue NSW]].<ref name="MSV">{{cite web |title=Marine radio |url=https://transportsafety.vic.gov.au/maritime-safety/recreational-vessel-operators/powerboat/trip-preparation/safety-equipment/marine-radio |website=transportsafety.vic.gov.au |publisher=Transport Safety Victoria |access-date=1 January 2019 |language=en}}</ref><ref>{{cite web |title=Marine Radios |url=https://www.marinerescuensw.com.au/boating-safety/marineradios |website=www.marinerescuensw.com.au |publisher=Marine Rescue NSW |access-date=1 January 2019}}</ref><ref>{{cite web |title=Radiocommunications (Maritime Ship Station — 27&nbsp;MHz and VHF) Class Licence 2015 |url=https://www.legislation.gov.au/Details/F2018C00926 |website=www.legislation.gov.au |date=28 November 2018 |publisher=Commonwealth of Australia |access-date=31 December 2018 |language=en}}</ref>

===Canada===
In [[Canada]], the [[Canadian Radio-television and Telecommunications Commission|CRTC]] officially calls the CB band the "General Radio Service", though regulations also note that this service is commonly called "CB".<ref>{{cite web |title=RIC-18 - General Radio Service |url=https://ised-isde.canada.ca/site/spectrum-management-telecommunications/en/licences-and-certificates/radiocom-information-circulars-ric/ric-18-general-radio-service-grs |website=Canada Radio-television and Telecommunications Commission |date=26 August 2002 |publisher=Government of Canada |access-date=30 May 2024}}</ref> Canada's GRS uses the identical frequencies and modes as the United States citizens band, and no special provisions are required for either Canadians or Americans using CB gear while traveling across the border.

The General Radio Service was authorized in 1962. Initially, CB channels&nbsp;1–3 remained allocated to amateur radio and channel&nbsp;23 was used by [[pager|paging services]]. American CB licensees were initially required to apply for a temporary license to operate in Canada.<ref>{{cite magazine |first=Matt P. |last=Spinello |title=Touring Canada with your CB rig |magazine=Elementary Electronics |publisher=Davis Publications |place=New York, NY |volume=10 |issue=2 |date=July–August 1972 |pages=55–56}}</ref> In April&nbsp;1977, the service was expanded to the same 40&nbsp;channels as the American service.<ref>{{cite web |publisher=Government of Canada Department of Communications |url=http://www.spectralumni.ca/Brochures/TRC-40.pdf |series=TRC 40 |title=Licensing of General Radio Service Equipment |archive-url=https://web.archive.org/web/20110706203636/http://www.spectralumni.ca/Brochures/TRC-40.pdf |archive-date=2011-07-06 |df=dmy-all |date=January 1, 1977 |access-date=3 Jan 2010}}</ref>

===Indonesia===
In [[Indonesia]], CB radios were first introduced about 1977 when some transceivers were imported illegally from Australia, Japan and the United States. The dates are hard to confirm accurately, but early use was known around large cities such as [[Jakarta]], [[Bandung]], [[Yogyakarta]], [[Surabaya]] and [[Medan]]. The Indonesian government legalized CB on 6&nbsp;October 1980 with a decision by the Minister of Communications, the "Ministerial Decree on the Licensing for the Operation of Inter-Citizens Radio Communication". Because many people were already using 40&nbsp;channel radios prior to legalization, the American band plan (with AM and SSB) was adopted; a [[Personal radio service#Indonesia|VHF band]] was added in 1994, along with allowing use of the Australian [[UHF CB]] channel plan at 476-477&nbsp;MHz On 10&nbsp;November 1980, the Indonesian Directorate General of Posts and Telecommunications issued another decree establishing RAPI (''Radio Antar Penduduk Indonesia'') as the official citizens band radio organization in Indonesia.<ref>{{cite web |url=http://cbradio.idxc.org/ |publisher=Indonesian DX Club |title=CB Radio |archive-url=https://web.archive.org/web/20070202205052/http://cbradio.idxc.org/ |archive-date=2007-02-02 |df=dmy-all}}</ref>

===Malaysia===
In Malaysia, citizens band radios became legal when the "Notification of Issuance Of Class Assignments" by the Malaysian Communication and Multimedia was published on 1&nbsp;April 2000. Under this class assignment, a CB radio is classified as a "Personal Radio Service device". The frequency band is HF, 26.9650&nbsp;MHz to 27.4050&nbsp;MHz (40 channels), power output is 4&nbsp;watts for AM and FM and 12&nbsp;watts PEP for SSB. Channel&nbsp;9 is reserved for emergencies, and channel&nbsp;11 is a calling channel. On UHF 477&nbsp;MHz, citizens band PRS radio devices are allowed 5 watts power output on FM on 39&nbsp;assigned channels spaced at 12.5&nbsp;kHz intervals from 477.0125 to 477.4875&nbsp;MHz. Channel&nbsp;9 is reserved for emergencies, and channel&nbsp;11 for calling. A short-range [[Simplex communication|simplex]] radio communications service for recreational use is from 477.5250 to 477.9875&nbsp;MHz FM mode with 38&nbsp;channels and a power output of 500&nbsp;mW. A CB radio or Personal Radio Service Device under Class Assignment does not need an individual license to operate in Malaysia if it adheres to the rules of the ''Warta Kerajaan Malaysia''<ref>{{cite book |series=Communication and Multimedia Act |year=1998 |id=Act 588 |title=Notification of Issuance Of Class Assignment |at=P.U.(B) 416 Jil.&nbsp;48, No.&nbsp;22(e) |chapter=Personal Radio Service Device |access-date=1 November 2004 |chapter-url=http://www.skmm.gov.my/link_file/registers/cma/ClassAssignment/pdf/Class%20Assign-BI-register.pdf |url-status=live |archive-url=https://web.archive.org/web/20101130012827/http://skmm.gov.my/link_file/registers/cma/ClassAssignment/pdf/Class%20Assign-BI-register.pdf |archive-date=2010-11-30 |df=dmy-all}}</ref>

On 1&nbsp;April 2010 the MCMC released a new regulation<ref>{{cite book |series=Notification of Issuance of Class Assignments |title=Communications and Multimedia Act 1998 Class Assignments No.&nbsp;1 of 2010 |url=http://sppd.skmm.gov.my/skmmgovmy/files/attachments/CA_01_April_2010.pdf |access-date=2018-01-19 |url-status=dead |archive-url=https://web.archive.org/web/20180119235306/http://sppd.skmm.gov.my/skmmgovmy/files/attachments/CA_01_April_2010.pdf |archive-date=2018-01-19 |df=dmy-all}}</ref> and later on 2017.<ref>{{cite web |url=https://www.skmm.gov.my/skmmgovmy/media/General/pdf/Class-Assignment-No-1-of-2017.pdf |title=Class Assignment No.&nbsp;1 of 2017 |access-date=2018-01-19 |url-status=live |archive-url=https://web.archive.org/web/20180119235218/https://www.skmm.gov.my/skmmgovmy/media/General/pdf/Class-Assignment-No-1-of-2017.pdf |archive-date=2018-01-19 |df=dmy-all}}</ref> This includes a new UHF PMR 446&nbsp;MHz allocation: an eight-channel [[Analog signal|analog]] Personal Mobile Radio 446&nbsp;MHz (Analog PMR446) with frequencies from 446.00625 to 446.09375&nbsp;MHz (12.5&nbsp;kHz spacing) FM with 0.5&nbsp;watt power output, and 16&nbsp;channels for [[Digital signal (signal processing)|Digital]] Personal Mobile Radio 446&nbsp;MHz (Digital PMR 446). Frequencies for Digital PMR 446 are from 446.103125 to 446.196875&nbsp;MHz with 6.25&nbsp;kHz [[channel spacing]] in 4FSK mode and a power output of 0.5&nbsp;watt. An unofficial citizens band radio club in Malaysia is the "Malaysia Boleh Citizen Radio Group", known as "Mike Bravo" (''Malaysia Boleh'').<ref>{{cite web |url=http://my27mhz.blogspot.com/|title=Senarai Keahlian |website=my27mhz.blogspot.com |access-date=8 May 2018 |url-status=live |archive-url=https://web.archive.org/web/20170914024808/http://my27mhz.blogspot.com/ |archive-date=14 September 2017}}</ref> Subsequently, the MCMC revoked 477&nbsp;MHz personal radio service as a class assignment on 1 January 2022.<ref>{{cite web |url=https://mcmc.gov.my/en/media/announcements/usage-of-personal-radio-service-device-s-477-0125 |title=Usage of Personal Radio Service Device(s) (477.0125 MHz to 477.4875 MHz and 477.5250 MHz to 477.9875 MHz)(Sixth Notice) |publisher=MCMC}}</ref>

===United Kingdom===
{{Main|CB radio in the United Kingdom}}
In the UK, a small but growing number of people were illegally using American CB radios during the late 1970s and early 1980s. The prominence of CB radio grew in Britain partly due to the success of novelty songs like C.W. McCall's "Convoy" and Laurie Lingo & The Dipsticks' "Convoy GB" in 1976 (both of which were Top&nbsp;5 hits). By 1980, CB radio was becoming a popular pastime in Britain; as late as the summer of 1981 the British government was still saying that CB would never be legalized on 27&nbsp;MHz, proposing a UHF service around 860&nbsp;MHz called "Open Channel" instead. However, in November 1981 (after high-profile public demonstrations) 40&nbsp;frequencies unique to the UK, known as the [[27 MHz CB27/81 Bandplan|27/81 Bandplan]] using FM were allocated at 27&nbsp;MHz plus 20&nbsp;channels on 934&nbsp;MHz (934.0125–934.9625&nbsp;MHz with 50&nbsp;kHz spacing). CB's inventor, [[Alfred J. Gross|Al Gross]], made the ceremonial first legal British CB call from [[Trafalgar Square]] in London.

The maximum power allowable on the MPT&nbsp;1320 27/81 system was 4&nbsp;watts (in common with the American system), although initially radios were equipped to reduce output power by 10&nbsp;[[Decibel|dB]] (to 0.4&nbsp;watts) if the antenna was mounted more than 7&nbsp;meters (23') above ground level. The power-reduction switch is also useful in reducing [[Electromagnetic interference|TV interference]]. MPT&nbsp;1320 also restricted antennas to a maximum length of 1.5&nbsp;meters (5'), with base loading being the only type permitted for 27&nbsp;MHz operation. Over the next several years antenna regulations were relaxed, with antenna length increasing to 1.65&nbsp;meters (5'5") and centre- or top-loading of the main radiating element permitted. On 1&nbsp;September 1987 the UK added the usual 40&nbsp;frequencies (26.965–27.405&nbsp;MHz) used worldwide, for a total of 80&nbsp;channels at 27&nbsp;MHz; antenna regulations were further relaxed, and the 934&nbsp;MHz band was withdrawn in 1998.

CB radio in the UK was deregulated in December&nbsp;2006 by the regulatory body [[Ofcom]], and CB radio in the UK is now license-free. The old MPT&nbsp;1320 27/81 band will continue to be available for the foreseeable future. On 27&nbsp;June 2014, changes were made by Ofcom to allow the use of AM & SSB modes on CB in the UK legally for the first time. The rules regarding non-approved radios and power levels above 4&nbsp;Watts on AM/FM and 12&nbsp;Watts on SSB still apply, despite deregulation. Persons using illegal equipment or accessories still risk prosecution, fines or confiscation of equipment, although this is rarely enforced. AM and SSB on the freeband and amplifier use are common among enthusiasts. [[Packet radio]] is legal in the UK, although not widely used. Internet gateway stations are also beginning to appear; although illegal on 27&nbsp;MHz, these units are connected to other CB stations around the world.

Although the use of CB radios in the UK is limited, they are still in use, especially with the farming community, truckers, off-roaders and mini-cab services.<ref>{{cite magazine |first=Finlo |last=Rohrer |date=August 14, 2006 |url=http://news.bbc.co.uk/2/hi/uk_news/magazine/4789887.stm |title=Over and out? |archive-url=https://web.archive.org/web/20110904005853/http://news.bbc.co.uk/2/hi/uk_news/magazine/4789887.stm |archive-date=2011-09-04 |df=dmy-all |magazine=BBC News Magazine |access-date=2011-10-22}}</ref> The widely used channel for the [[National Federation of Young Farmers' Clubs|Young Farmers' Club]] is channel&nbsp;11. The normal calling and truckers' channel is channel 19, although many truck organisations and groups use other channels to avoid abuse.

==Frequency allocations==
CB radio is not a worldwide, standardized radio service. Each country decides if it wants to authorize such a radio service from its domestic frequency authorizations, and what its standards will be; however, similar radio services exist in many countries. Frequencies, power levels and modes (such as [[frequency modulation]] (FM), [[amplitude modulation]] (AM), and [[single-sideband modulation]] (SSB), often vary from country to country; use of foreign equipment may be illegal. However, many countries have adopted the American channels and their associated frequencies, which is generally in AM mode except some higher channels which are sometimes in SSB mode. In September 2021 the FCC approved the use of FM on CB radio.<ref>{{cite web |title=Citizens Band (CB) Scanner Frequencies and Radio Frequency Reference |url=http://www.radioreference.com/apps/db/?aid=7731 |website=radioreference.com |access-date=2015-10-08 |df=dmy-all |url-status=live |archive-url=https://web.archive.org/web/20150914173859/http://www.radioreference.com/apps/db/?aid=7731 |archive-date=2015-09-14}}</ref>

=== Standard channels ===
The standard channel numbering is harmonized through the [[Federal Communications Commission|FCC]] ([[United States|USA]]) and the [[European Conference of Postal and Telecommunications Administrations|CEPT]] ([[Europe]]).{{efn|Channels 23&nbsp;[27.235&nbsp;MHz], 24&nbsp;[27.245&nbsp;MHz], and 25&nbsp;[27.255&nbsp;MHz] are not on the same radio frequencies in the [[European Conference of Postal and Telecommunications Administrations|CEPT]] standard.}}<ref name="legifrance.gouv.fr">{{cite web |url=http://www.legifrance.gouv.fr/affichTexte.do?cidTexte=JORFTEXT000000325971&categorieLien=cid |title=Arrêté du 31 mars 1992 relatif aux caractéristiques techniques et aux conditions d'exploitation des postes C.B. |website=legifrance.gouv.fr |access-date=8 May 2018 |url-status=live |archive-date=1 July 2017 |archive-url=https://web.archive.org/web/20170701032657/https://www.legifrance.gouv.fr/affichTexte.do?cidTexte=JORFTEXT000000325971&categorieLien=cid}}</ref>

See also [[CB usage in the United States#Channel assignments|channel assignments for CB use in the United States]].
{| class="wikitable" align="center" text-align="right"
|+ CB Radio Channels ([[Federal Communications Commission|FCC]])<ref name="95.407">{{cite web |url=http://frwebgate.access.gpo.gov/cgi-bin/get-cfr.cgi?TITLE=47&PART=95&SECTION=407&YEAR=2000&TYPE=TEXT |title=(CB Rule&nbsp;7) On what channels may I operate? |website=frwebgate.access.gpo.gov |access-date=8 May 2018 |url-status=live |archive-url=https://web.archive.org/web/20090214183927/http://frwebgate.access.gpo.gov/cgi-bin/get-cfr.cgi?TITLE=47&PART=95&SECTION=407&YEAR=2000&TYPE=TEXT |archive-date=14 February 2009}}</ref>
|- style="text-align:right"
! Ch.
! Frequency
!
! Ch.
! Frequency
!
! Ch.
! Frequency
!
! Ch.
! Frequency
!
! Ch.
! Frequency
|- style="text-align:right"
| 1
| 26.965&nbsp;MHz
|
| 9
| 27.065&nbsp;MHz
|
| 17
| 27.165&nbsp;MHz
|
| *25
| 27.245&nbsp;MHz
|
| 33
| 27.335&nbsp;MHz
|- style="text-align:right"
| 2
| 26.975&nbsp;MHz
|
| 10
| 27.075&nbsp;MHz
|
| 18
| 27.175&nbsp;MHz
|
| 26
| 27.265&nbsp;MHz
|
| 34
| 27.345&nbsp;MHz
|- style="text-align:right"
| *3
| 26.985&nbsp;MHz
|
| *11
| 27.085&nbsp;MHz
|
| *19
| 27.185&nbsp;MHz
|
| 27
| 27.275&nbsp;MHz
|
| 35
| 27.355&nbsp;MHz
|- style="text-align:right"
| 4
| 27.005&nbsp;MHz
|
| 12
| 27.105&nbsp;MHz
|
| 20
| 27.205&nbsp;MHz
|
| 28
| 27.285&nbsp;MHz
|
| 36
| 27.365&nbsp;MHz
|- style="text-align:right"
| 5
| 27.015&nbsp;MHz
|
| 13
| 27.115&nbsp;MHz
|
| 21
| 27.215&nbsp;MHz
|
| 29
| 27.295&nbsp;MHz
|
| 37
| 27.375&nbsp;MHz
|- style="text-align:right"
| 6
| 27.025&nbsp;MHz
|
| 14
| 27.125&nbsp;MHz
|
| 22
| 27.225&nbsp;MHz
|
| 30
| 27.305&nbsp;MHz
|
| 38
| 27.385&nbsp;MHz
|- style="text-align:right"
| *7
| 27.035&nbsp;MHz
|
| *15
| 27.135&nbsp;MHz
|
| *23
| 27.255&nbsp;MHz
|
| 31
| 27.315&nbsp;MHz
|
| 39
| 27.395&nbsp;MHz
|- style="text-align:right"
| 8
| 27.055&nbsp;MHz
|
| 16
| 27.155&nbsp;MHz
|
| *24
| 27.235&nbsp;MHz
|
| 32
| 27.325&nbsp;MHz
|
| 40
| 27.405&nbsp;MHz
|-
|}

:<nowiki>*</nowiki> Channels&nbsp;3, 7, 11, 15, and 19 have adjacent "hidden" channels (see below); channels&nbsp;23, 24, and 25 are numbered out-of-order for their frequency allocations in the United States.

=== Intermediate channels ===
When looking at the FCC/CEPT channel list there are some channels with a spacing of 20&nbsp;kHz instead of the regular 10&nbsp;kHz step. These intermediate frequencies are reserved for the Radio Control Radio Service (RCRS).{{efn|RCRS was formerly known as the Class C Citizens Radio Service until the 1976 changes.}} The RCRS service is commonly used for remote control of model aircraft and boats. It is an unofficial practice to name these channels by their next lower standard channel number along with a suffix&nbsp;"A" (''after''). For example, channel&nbsp;"11A" is 27.095&nbsp;MHz, spaced 10&nbsp;kHz <u>after</u> standard channel&nbsp;11 (at 27.085&nbsp;MHz) is used to provide for part of European railroad's [[Eurobalise]] radio communication with trains.

{| class="wikitable"
! Channel !! Frequency !! Channel !! Frequency !! Channel !! Frequency !! Channel !! Frequency !! Channel !! Frequency
|-
| ''3A'' || 26.995&nbsp;MHz ||  ''7A'' || 27.045&nbsp;MHz || ''19A'' || 27.195&nbsp;MHz || ''11A'' || 27.095&nbsp;MHz || ''15A'' || 27.145&nbsp;MHz
|}

=== SSB use ===
{{Unreferenced section|date=October 2015}}
[[Single-sideband modulation|Single-sideband]] (SSB) operation involves the selection of either the Lower Side Band (LSB) or the Upper Side Band (USB) mode for transmit and receive.  SSB radios also have the standard AM mode for communicating with standard CB radio models. With the original 23&nbsp;CB channels SSB stations commonly used channel&nbsp;16, to avoid interference to those using [[Amplitude modulation|AM]] (SSB stations are authorized to use 12&nbsp;watts, as opposed to 4&nbsp;watts for AM stations) and to more easily locate other SSB stations. With the FCC authorization of 40&nbsp;channels, SSB operation shifted to channels&nbsp;36–40. Channel&nbsp;36 (or 38 for LSB) became the unofficial SSB "calling channels" for stations seeking contacts, with the subsequent conversation moving to channels&nbsp;37–40. CBers with AM-only radios are asked to not use channels&nbsp;36 through 40. In return, SSB stations stay off the remaining 35&nbsp;channels so they could be used by AM stations. This agreement provides interference-free operation for all operators by separating the far more powerful SSB stations from the AM stations. This solution also resolves the confusion created by the false advertising that SSB radios have 120&nbsp;channels compared to only 40 for AM radios.

While a SSB radio has three possible "modes" (AM, LSB, USB) it can operate in, operation is still limited to the same 40&nbsp;channels. Some manufacturers tried to sell more radios by claiming that with three different modes possible for each channel, it was the equivalent to 120&nbsp;channels.{{Citation needed|date=October 2020}}  Reality is far different: Attempting an SSB conversation while an AM conversation is in progress results in jammed communications for everyone. In general, each channel can only support one AM conversation and no others; if no AM conversation is in progress, two SSB conversations can share one channel without interference if one is in LSB and the other in USB mode. For a particular conversation, everyone must be tuned to the same channel and same mode in order to talk with each other.
Starting in October 2021 the FCC has approved FM for CB in the US.

=== Country-specific variations ===
{{Main|Personal radio service}}
The [[European Conference of Postal and Telecommunications Administrations]] (CEPT) adopted the North American channel assignments, except channel&nbsp;23, frequency 27.255&nbsp;MHz; channel&nbsp;24, frequency 27.235&nbsp;MHz; and channel&nbsp;25, frequency 27.245&nbsp;MHz.<ref name="legifrance.gouv.fr"/> However, legal CB equipment sold in Europe does follow the North American channel designation. Some member countries permit additional modes and frequencies; for example, [[Germany]] has 40&nbsp;additional channels at 26&nbsp;MHz for a total of 80. The [[United Kingdom]] has an additional 40&nbsp;channels between 27.60125 and 27.99125&nbsp;MHz, also making 80&nbsp;channels in total. Before CEPT, most member countries used a subset of the 40&nbsp;U.S. channels.

In [[Russia]] and [[Poland]], the channels are shifted 5&nbsp;kHz down; for example, channel&nbsp;30 is 27.300&nbsp;MHz.{{citation needed|date=November 2011}} Many operators add a switch to change between the "zeroes" (the Russian/Polish channel assignment) and the "fives" (the international/European assignment). Most contemporary radios built for those markets can do "fives" as well as "zeroes" out of the box. Since roughly 2005–2006, Russia and Poland have adopted use of the standard US channel offset as well as the older channel plan, for two overlapping "grids" of channels.

Russia uses an alphanumeric designation for their CB channel plans, because several "grids" or "bands" of 40&nbsp;channels each are used, along with both AM and FM mode.  Russian CB allocations follow the CB band 26.965–27.405&nbsp;MHz (designated as band&nbsp;C), as well as 26.515–26.955&nbsp;MHz (designated as band&nbsp;B) and 27.415–27.855&nbsp;MHz (designated as band&nbsp;D). Some radios refer to the "mid band" (standard CB band) as "band&nbsp;D" which shifts the letters up one (making 26.515–26.955&nbsp;MHz "band&nbsp;C" and 27.415–27.855&nbsp;MHz "band&nbsp;E".

For the convenience of users of the grid were marked by letters. Classic is considered the marking when the main range is designated letter&nbsp;"C". The most common description of the channel is considered to be similar to the following: (C9FM or C9EFM or C9EF or 9EF).

In it:

* the first letter («C») is indicated by a grid that contains a set of 40&nbsp;channels. If the first letter is not specified, it is considered that it is («C»). For example, (C9EF, 9EF)
* hereinafter ("9") – the channel number. Sometimes less than 10&nbsp;channels are designated 2&nbsp;digits. For example, (C9EF, C09EF)
* behind it – an optional designation («E») for "European" or mandatory («R») for "Russian" size frequency nets. For example, (C9EF, C9F, C9RF)
* end – the used modulation («FM») or («F»), («AM») or («A»). e.g. (C9EFM, C9EF, C9EAM, C9EA)

An example of correct designations: C9EF, C9EA, C9RF, C9RA

The 25–30&nbsp;MHz band (including the CB allocations and frequencies above and below the 26.5–27.860&nbsp;MHz band) is heavily used for taxi cab and other mobile two-way communications systems in Russia, Ukraine and other former USSR country states.

[[New Zealand]] and [[Japan]] have unique allocations compared to any other country. New Zealand authorizes use of their New Zealand specific 40&nbsp;channel 26.330–26.770&nbsp;MHz [[frequency plan]] in addition to the "standard" 40&nbsp;channel 26.965–27.405&nbsp;MHz frequency plan for a total of 80&nbsp;HF CB channels. New Zealand has adopted the Australian UHF CB System as well.<ref>{{cite web |url=http://www.uhfcb.com.au/New-Zealand-PRS.php |publisher=UHF CB Australia - New Zealand PRS |department=News |title=Repeater Locations & Information |website=www.uhfcb.com.au |access-date=8 May 2018 |url-status=live |archive-url=https://web.archive.org/web/20180312193015/http://uhfcb.com.au/New-Zealand-PRS.php |archive-date=12 March 2018}}</ref>

Japan's CB allocation consists of 8&nbsp;voice and 2&nbsp;radio control channels with a maximum power output of 500&nbsp;mW. AM mode is the only mode permitted and antennas must be non-removable and less than 199&nbsp;cm (78&nbsp;inches) long. In Japan, the 26–28&nbsp;MHz range is allocated to fishery radio services and these frequencies are heavily used for marine communications. Japan's "double side band fishery radio" or "DSB Fishery Radio Service" covers 26.760&nbsp;MHz-26.944&nbsp;MHz, 27.016&nbsp;MHz, and 27.524-27.988&nbsp;MHz. However, frequencies such as 27.005&nbsp;MHz AM are widely pirated in Japan with very high power transmitters. This causes interference to the authorized low-power 1&nbsp;Watt DSB (1&nbsp;Watt AM) fishery radio service. Instead of 26–27&nbsp;MHz, Japan has authorized several UHF FM CB-type [[personal radio service#Japan|personal radio service]]s in the 348&nbsp;MHz, 420–422&nbsp;MHz and 903–904&nbsp;MHz bands.

# 26.968&nbsp;MHz – Japanese CB Channel 1
# 26.976&nbsp;MHz – Japanese CB Channel 2
# 27.040&nbsp;MHz – Japanese CB Channel 3
# 27.080&nbsp;MHz – Japanese CB Channel 4
# 27.088&nbsp;MHz – Japanese CB Channel 5
# 27.112&nbsp;MHz – Japanese CB Channel 6
# 27.120&nbsp;MHz – Japanese CB Channel 7
# 27.144&nbsp;MHz – Japanese CB Channel 8 – Calling Channel

# 27.048&nbsp;MHz – Japanese Remote Control R/C Frequency
# 27.136&nbsp;MHz – Japanese Remote Control R/C Frequency
# 27.152&nbsp;MHz – Japanese Remote Control R/C Frequency

[[Indonesia]] has the usual 40&nbsp;channels at 27&nbsp;MHz, plus a unique 60-channel VHF allocation from 142.050 to 143.525&nbsp;MHz. Unlike most other countries, CB operators in Indonesia are required to have a CB-specific license (similar to GMRS licensing in the United States, albeit it cannot be used by other immediate family members and only valid for 5 years). An alphanumeric callsign, like it's amateur radio counterpart, would then be issued. <ref>{{cite web |url=http://www.postel.go.id/content/ID/regulasi%5Cfrekuensi%5Ckepmen%5Ckm%20nomor%2077-2003%20krap.pdf |title=An Indonesian government decision regarding CB, with frequency charts |archive-url=https://web.archive.org/web/20160120224026/http://www.postel.go.id/content/ID/regulasi/frekuensi/kepmen/km%20nomor%2077-2003%20krap.pdf |archive-date=2016-01-20 |df=dmy-all}}</ref>

In [[Brazil]], CB channels were upgraded from 23 to 60 channels starting in 1979 and again in 1980 to {{ill|lt=80 channels|Serviço Rádio do Cidadão#Frequência e canalização|pt|vertical-align=sup}} (from 26.965&nbsp;MHz to 27.855&nbsp;MHz).

'''CB Radio Channels (ANATEL)'''
{| class="wikitable"
|Channel
|Frequency
|Channel
|Frequency
|-
|1
|26.965
|41
|27.415
|-
|2
|26.975
|42
|27.425
|-
|3
|26.985
|43
|27.435
|-
|4
|27.005
|44
|27.455
|-
|5
|27.015
|45
|27.465
|-
|6
|27.025
|46
|27.475
|-
|7
|27.035
|47
|27.485
|-
|8
|27.055
|48
|27.505
|-
|9
|27.065
|49
|27.515
|-
|10
|27.075
|50
|27.525
|-
|11
|27.085
|51
|27.535
|-
|12
|27.105
|52
|27.555
|-
|13
|27.115
|53
|27.565
|-
|14
|27.125
|54
|27.575
|-
|15
|27.135
|55
|27.585
|-
|16
|27.155
|56
|27.605
|-
|17
|27.165
|57
|27.615
|-
|18
|27.175
|58
|27.625
|-
|19
|27.185
|59
|27.635
|-
|20
|27.205
|60
|27.655
|-
|21
|27.215
|61
|27.665
|-
|22
|27.225
|62
|27.675
|-
|23
|27.255
|63
|27.705
|-
|24
|27.235
|64
|27.685
|-
|25
|27.245
|65
|27.695
|-
|26
|27.265
|66
|27.715
|-
|27
|27.275
|67
|27.725
|-
|28
|27.285
|68
|27.735
|-
|29
|27.295
|69
|27.745
|-
|30
|27.305
|70
|27.755
|-
|31
|27.315
|71
|27.765
|-
|32
|27.325
|72
|27.775
|-
|33
|27.335
|73
|27.785
|-
|34
|27.345
|74
|27.795
|-
|35
|27.355
|75
|27.805
|-
|36
|27.365
|76
|27.815
|-
|37
|27.375
|77
|27.825
|-
|38
|27.385
|78
|27.835
|-
|39
|27.395
|79
|27.845
|-
|40
|27.405
|80
|27.855
|}

[[South Africa]], like New Zealand and the UK, permits the use of two HF CB bands.  South Africa has a 23&nbsp;channel AM / SSB 29&nbsp;MHz CB allocation (called "29 Megs" or "29 MHz CB") from 29.710 to 29.985&nbsp;MHz in 12.5&nbsp;kHz steps. South Africa also permits use of standard CB channels&nbsp;19–27 (27.185–27.275&nbsp;MHz) with AM / SSB permitted. Many radios sold in South Africa feature both the 27&nbsp;MHz and 29&nbsp;MHz bands. A license from [[ICASA]] is no longer required to purchase or use a CB radio in South Africa.

[[Hungary]] allows use of the "low channels" for a total of 80&nbsp;channels (26.515&nbsp;MHz to 27.405&nbsp;MHz).

[[Germany]] authorizes a similar allocation, with 40&nbsp;channels from 26.965 to 27.405&nbsp;MHz and another 40&nbsp;channels from 26.565 to 26.955&nbsp;MHz in regular 10-kHz steps.

The [[Czech Republic]] authorizes 80 channels as well (same as the German 80-channel plan). As in Germany, digital modes are allowed on certain frequencies.{{efn|Channels&nbsp;24&nbsp;[27.235&nbsp;MHz], 25&nbsp;[27.245&nbsp;MHz], 52&nbsp;[26.675&nbsp;MHz], 53&nbsp;[26.685&nbsp;MHz], 76&nbsp;[26.915&nbsp;MHz, and channel&nbsp;77&nbsp;[26.925&nbsp;MHz]}} [[Gateway (telecommunications)|Internet gateways]] and [[radio repeater]]s are allowed on channels 18&nbsp;[27.175&nbsp;MHz] and 23&nbsp;[27.255&nbsp;MHz]. Paging is permitted on channel&nbsp;1 (26.965&nbsp;MHz) and channel&nbsp;80 (26.955&nbsp;MHz) is the recommended call channel for Czech CB radio operators.

Using radios outside their intended market can be dangerous, as well as illegal, as frequencies used by Citizen's Band radios from other countries may operate on frequencies close to, or be used by, emergency services (for example, the Indonesian service around 142&nbsp;MHz operates on frequencies allocated to a public safety network shared with police, fire and EMS services in Ontario, Canada).

In the [[Philippines]], up to present time, the use of 27&nbsp;MHz CB is still banned since the Marcos regime banned it in 1980s. Before it was banned, they use the same allocation as the US. A few operators still illegally utilize the 40&nbsp;CB channels.

=={{anchor|Usage today}}Current use==
CB was the only practical two‑way radio system for the individual consumer, and served several subsets of users such as truck drivers, radio hobbyists, and those in need of short‑range radio communications, such as electricians, plumbers, and carpenters, who needed to communicate between job site and main office. While some users have moved on to other radio services, CB is still a popular [[hobby]] in many countries. The 27&nbsp;MHz frequencies used by CB, which require a relatively long aerial antennas and tend to propagate poorly indoors, discourage the use of handheld radios. Many users of handheld radios (families, hunters and hikers) have moved on to 49&nbsp;MHz and the UHF [[Family Radio Service]]; those needing a simple radio for professional use (e.g., tradesmen) have moved on{{citation needed|date=February 2022}} to "dot-color" Business Band radios and the VHF [[Multi-Use Radio Service]].

CB is still commonly used by long-haul truck drivers to communicate directions, traffic problems and other relevant matters.<ref>{{cite book |first=Alice |last=Adams |title=Trucking: Tractor-Trailer Driver Handbook/Workbook |page=558 |chapter-url=https://books.google.com/books?id=Lg3rFnEkOPQC&pg=PA558 |chapter=The first CB radio|date=28 November 2005 |publisher=Delmar Cengage Learning |isbn=9781418012625 }}</ref> The unofficial "travelers channel" in most of the world is channel&nbsp;19; in Australia it is channel&nbsp;8 (27.055&nbsp;MHz) and UHF channel&nbsp;40 (477.400&nbsp;MHz). In Russia, it is channel&nbsp;15 (in addition to traditional emergency channel&nbsp;9 and truckers' channel&nbsp;19), in Greece it is channel&nbsp;13, in Italy it is channel&nbsp;5, all AM. These frequencies may have evolved because tuned circuits (particularly antennas) work best in the middle of the band; the frequency for channel&nbsp;19 (not channel&nbsp;20) is the center of the 40&nbsp;channel US band and other things being equal, signals will be transmitted and heard the farthest. Since less standardization exists in Europe, CB there is more associated with hobbyists than with truckers.

Legal (short‑range) use of CB radio is sometimes impeded by users of illegal high‑power transmitters, which can be heard hundreds of miles away. The other problem with short‑range CB use is propagation; during long‑range [[Skywave|"skip"]] conditions local signals are inaudible due to reception of multiple distant signals.

In the United States, the number of users and law enforcement financing by the [[Federal Communications Commission]] mean that only the worst offenders are sanctioned, which makes legitimate operation on the citizens band unreliable. Most offenders are not caught for interfering with other CB users; often, their self‑modified equipment generates [[harmonic]]s and [[Spurious tone|spurs]] which cause interference to services outside the citizens band and to consumer equipment.

The maximum legal CB power output level in the U.S. is 4&nbsp;watts for AM (un-modulated carrier; modulation can be four times the carrier power, or 16&nbsp;watts [[Peak envelope power|PEP]]) and 12&nbsp;watts for [[single-sideband modulation|SSB]], as measured at the transmitter antenna connection.  However, external [[linear amplifier]]s are often used illegally.

During the 1970s, the FCC banned the sale of linear amplifiers capable of operation from 24 to 35&nbsp;MHz to discourage their use on the CB band, although the use of high‑power amplifiers continued. Late in 2006, the FCC amended the regulation to exclude only 26–28&nbsp;MHz to facilitate amateur 10&nbsp;meter operation.<ref>{{cite web |url=http://cbradiosource.com/cb-info/archives#fccOmnibus |title="Omnibus" Amateur Radio Report and Order|website=cbradiosource.com |access-date=8 May 2018 |url-status=dead |archive-url=https://web.archive.org/web/20140813044934/http://cbradiosource.com/cb-info/archives#fccOmnibus |archive-date=13 August 2014}}</ref> Lax enforcement enables manufacturers of illegal linear amplifiers to openly advertise their products; many CB dealers include these amplifiers in their catalogs. Due to their rampant, unchecked use of linear amplifiers, American CB Radio operators are often referred to as "Alligators", by operators in other countries (suggesting American operators are "All Mouth and No Ears"). Attempts by law-abiding CB users to increase regulatory oversight have been ineffective.

==Technology==
At the beginning of the CB radio service, transmitters and receivers used [[vacuum tube]]s; solid-state transmitters were not widely available until 1965, after the introduction of RF power-[[transistor]]s.<ref>{{cite web |url=http://www.qsl.net/k5dh/raytheon/raytheon.html |title=Raytheon |access-date=2009-08-21 |df=dmy-all |url-status=live |archive-url=https://web.archive.org/web/20100424214057/http://www.qsl.net/k5dh/raytheon/raytheon.html |archive-date=2010-04-24}} gives the history of one US manufacturer's line of CB equipment</ref> [[Walkie-talkie]] hand-held units became affordable with the use of transistors. Early receivers did not cover all the channels of the service; channels were controlled by plug-in quartz [[crystal oscillator|crystals]], with one of several operating frequencies selected by a panel control in more expensive units. [[Superheterodyne]] receivers (using one or two conversion stages) were the norm in good-quality equipment, although low-cost toy-type units used [[Regenerative circuit#Super-regenerative receiver|super-regenerative]] receivers. With the earliest sets two quartz crystals were needed for transmitting and receiving on each channel, which was costly. By the mid-1960s "mixer" circuits made frequency-synthesized radios possible, which reduced cost and allowed full coverage of all 23&nbsp;channels with a smaller number of crystals (typically&nbsp;14). The next improvement came during the mid-1970s; crystal synthesis was replaced by [[Phase-locked loop|PLL]] technology using ICs, enabling 40&nbsp;channel sets with only one crystal (10.240&nbsp;MHz). Almost all were [[Amplitude modulation|AM]]-only, although there were a few [[single-sideband modulation|single sideband]] sets.

Most CB radios sold in the United States have the following features:
* Automatic noise limiter or [[noise blanker]]: Reduces background noise (such as spark ignition)
* CB / [[NOAA Weather Radio|WX]] switch: Selects weather-radio receiver
* [[Automatic level control]] (ALC): Limits the transmitter modulation level to reduce distortion
* [[Public address system|PA]]: Some transceivers can drive an external speaker and act as a low-power public address system, or "bullhorn".
* RF gain: Adjusts the RF amplifier gain of the receiver; used to reduce received background noise, and to reduce "clipping" due to over-amplification of already-strong signals (for example, when the receiver is near the transmitter)
* NOR / 9 / 19: Quickly tunes preset channels for calling or emergency use
* [[Standing wave ratio|SWR]]: Meter used to monitor reflected power caused by [[Electrical length|mismatched antennas]] and [[Characteristic impedance|antenna cables]]
* Volume control

[[Microphone]] choices include:
* [[Microphone#Dynamic microphone|Dynamic microphone]]: Uses magnetic coil and permanent magnet
* Ceramic mic: Uses a [[Piezoelectricity|piezoelectric]] element; rugged, low-cost but high-[[Electrical impedance|impedance]]
* Echo mic: Deliberately introduces distortion and echo into transmitted audio
* [[Electret microphone]]: Uses an electrostatic method to convert sound to electrical signals
* [[Noise-canceling microphone]]: Uses two elements to reduce background noise
* Power mic: An amplified microphone<ref>{{cite web |url=http://www.newcompanydriver.com/cb-basics.htm |series=New Company Driver |title=Learn the basics of CB radio |archive-url=https://web.archive.org/web/20081001182648/http://newcompanydriver.com/cb-basics.htm |archive-date=2008-10-01 |df=dmy-all}}</ref>

==Antennas==
[[File:CB antenna.jpg|thumb|Typical center-loaded mobile CB antenna. Note the [[loading coil]], which shortens the antenna's overall length.|alt=A tall antenna with a helical coil in the middle, mounted on pickup-truck metal tool box]]

27&nbsp;MHz is a relatively long wavelength for mobile communications, and the choice of antenna has a considerable impact on the performance of a CB radio. A common mobile antenna is a quarter-wave vertical whip. This is roughly 9&nbsp;feet (2.7&nbsp;m) tall; it is mounted low on the vehicle body, and often has a spring-and-ball mount to enhance its flexibility when scraping or striking overhead objects. Where a nine-foot whip is undesirable, shorter antennas include [[loading coil]]s to make the antenna impedance the same as a physically longer antenna.  The loading coil may be on the bottom, middle, or top of the antenna, while some antennas are wound in a continuously loaded helix.

Many truckers use two co-phased antennas, mounted on their outside mirrors. Such an array is intended to enhance performance to the front and back, while reducing it to the sides (a desirable pattern for long-haul truckers). To achieve this effect, the antennas must be separated by about eight feet, only practical on large trucks. Two antennas may be installed for symmetrical appearance, with only one connected.

Another mobile antenna is the continuously loaded half-wave version. They do not require a [[ground plane]] to present a near-50&nbsp;[[ohm]] load to the radio, and are often used on fiberglass vehicles such as snowmobiles or boats. They are also useful in base stations where circumstances preclude the use of a ground-plane antenna. Handheld CBs may use either a telescoping center-loaded whip or a continuously loaded "rubber ducky" antenna.

Base CB antennas may be vertical for omnidirectional coverage, or directional "beam" antennas may be used to direct communications to a particular region. Ground-plane kits exist as mounting bases for mobile whips, and have several wire terminals or hardwired ground radials attached. These kits are designed to have a mobile whip screwed on top (a full-length, quarter-wave steel whip is preferred) and mounted on a mast. The ground radials replace the vehicle body (which is the [[Counterpoise (ground system)|counterpoise]] for a mobile whip in a typical vehicle installation).

==Skywave<span class="anchor" id="Shooting skip"></span>==
{{Main|Skywave}}

All frequencies in the [[high frequency|HF]] spectrum (3–30&nbsp;MHz) can be refracted by charged ions in the [[ionosphere]]. Refracting signals off the ionosphere is called [[skywave]] propagation, and the operator is said to be "shooting skip". CB operators have communicated across thousands of miles and sometimes around the world. Even low-power 27&nbsp;MHz signals can sometimes propagate over long distances.

In times of high [[Solar cycle|sunspot]] activity, the band can remain open to much of the world for long periods of time. During low sunspot activity it may be impossible to use skywave at all, except during periods of [[Sporadic E propagation|Sporadic-E propagation]] (from late spring through mid-summer). Skip contributes to noise on CB frequencies. In the United States, it is no longer illegal to engage in (or attempt to engage in) CB communications with any station more than {{convert|250|km|mi|abbr=on}} from an operator's location.<ref>FCC regulations Part&nbsp;95 Subpart&nbsp;D.</ref> This restriction used to exist to keep CB as a local (line-of-sight) radio service; however, in the United States the restriction has been dropped. The legality of shooting skip is not an issue in most other countries. A recent FCC decision now allows shooting skip in the United States.<ref>{{cite web |url=http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf01016.html#General |title=RIC-18 — General Radio Service (GRS) |publisher=Government of Canada |agency=Innovation, Science and Economic Development Canada |department=Office of the Deputy Minister, Spectrum, Information Technologies, and Telecommunications |website=IC.GC.ca |date=26 August 2002 |url-status=live |archive-url=https://web.archive.org/web/20170615020420/http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf01016.html#General |archive-date=15 June 2017 |access-date=8 May 2018 }}</ref>

==Freebanding and export radios==
Operation on frequencies above or below the citizens band (on the "uppers" or "lowers") is called "freebanding" or "outbanding".{{efn|The term "outbanding" was introduced by Kneitel in the August&nbsp;1979 issue of ''S9&nbsp;Magazine''.<ref name=Kneitel1988/>{{rp|16}} }} While frequencies just below the CB segment (or between the CB segment and the amateur radio [[10-meter band]]) seem quiet and under-utilized, they are allocated to other radio services (including government agencies) and unauthorized operation on them is illegal. Furthermore, illegal transmitters and amplifiers may not meet good engineering practice for harmonic distortion or "[[Spectral splatter|splatter]]", which may disrupt other communications and make the unapproved equipment obvious to regulators. Freebanding is done with modified CB or amateur equipment, foreign CB radios which may offer different channels, or with radios intended for export. Legal operation in one country may be illegal in another; for example, in the UK until June&nbsp;2014 only 80&nbsp;FM channels were legal.

Unlike amateur radios with continuous frequency tuning, CBs manufactured for export are channelized. Frequency selection resembles that of modified American CBs more than any foreign frequency plan. They typically have a knob and display that reads up to channel&nbsp;40, but include an extra band selector that shifts all 40&nbsp;channels above or below the band and a "+10&nbsp;kHz" button to reach the model control "A"&nbsp;channels. These radios may have 6 or even 12&nbsp;bands, establishing a set of quasi-CB channels on many unauthorized frequencies. The bands are typically lettered A through F, with the normal citizens band as D.

For example, a freebander with an export radio who wants to use 27.635&nbsp;MHz would choose channel&nbsp;19 (27.185&nbsp;MHz) and then shift the radio up one band (+450&nbsp;kHz). It requires arithmetic on the part of the operator to determine the actual frequency, although more expensive radios include a [[frequency counter]] or a frequency display — two different components, providing an identical result. Illegal operations may unintentionally end up on frequencies very much in use. For instance, channel&nbsp;19 shifted two bands up is 28.085&nbsp;MHz, which is in a Morse code / data-only part of the 10&nbsp;meter ham band. Voice transmissions in a Morse code-only segment are easily detectable by authorities. Amateur Radio Service operators record, locate, and report to the FCC frequency trespassing and intrusions of their frequency allocations by pirate transmissions or illegal operators for enforcement action.<ref>{{cite web |url=http://www.arrl.org/fcc-enforcement-1 |title=FCC Enforcement |website=www.arrl.org |access-date=8 May 2018|url-status=live |archive-url=https://web.archive.org/web/20170910164423/http://www.arrl.org/fcc-enforcement-1 |archive-date=10 September 2017}}</ref>

Many freeband operators use [[amateur radio]]s modified to transmit out of band, which is illegal in some countries. Older amateur radios may require component changes; for instance, the 1970s [[Yaesu FT-101]] was modified for CB by replacing a set of crystals used to tune portions of the 10&nbsp;meter band, although some variants of the FT-101 were sold with the US FCC channels standard and were capable of transmitting above and below the legal 40&nbsp;channels by another 10&nbsp;or more channels.<ref name=Kneitel1988/>{{rp|174}} On some newer radios, the modification may be as simple as disconnecting a jumper wire or a diode. Many types of amateur transceivers may be found on CB and freeband, ranging from full-coverage HF transceivers to simpler [[10 meters|10&nbsp;meter]] mobile radios. In the United States, the FCC bans the importation and marketing of radios it deems easily modifiable for CB;<ref>{{cite web |url=https://swap.qth.com/fcc/fcc-cbtable2.htm |title=QTH.COM: FCC information regarding Illegal CB Radios|website=swap.qth.com |access-date=8 May 2018 |url-status=live |archive-url=https://web.archive.org/web/20171109065038/https://swap.qth.com/fcc/fcc-cbtable2.htm |archive-date=9 November 2017}}</ref> it is illegal to transmit on CB frequencies with a ham radio except in emergencies where no other method of communication is available.

A [[gray market]] trade in imported CB gear exists in many countries. In some instances, the sale or ownership of foreign-specification CB gear is not illegal but its use is.  With the FCC's minimal enforcement of its CB rules, enthusiasts in the US use "export radios" or European [[frequency modulation]] (FM) CB gear to escape the crowded AM channels. American AM gear has also been exported to Europe.

"Export radios" are sold in the United States as [[10 meters|10&nbsp;meter]] Amateur Radio transceivers. Marketing, import and sale of such radios is illegal if they are distributed as anything ''other'' than Amateur Radio transceivers. It is also illegal to use these radios outside of the Amateur Radio bands by anyone in the US, since they are not type-certified for other radio services and usually exceed authorized power limits. The use of these radios within the Amateur Radio Service by a licensed Amateur Radio operator within his / her license privileges is legal, as long as all FCC regulations for Amateur Radio are followed.

==Callbook==
A callbook is a directory of radio station call signs. Originally a bound book that resembled a telephone directory, it contains the name and addresses of radio stations in a given jurisdiction (country). ''[[Modern Electrics]]'' published the first callbook in the United States in 1909. Today, the primary purpose of a callbook is to allow radio operators to send a confirmation post card, called a [[QSL card]], to an operator with whom they have communicated via radio. Callbooks have evolved to include online databases that are accessible via the Internet to instantly obtain the address of another amateur radio operator and their QSL managers. The most well known and used on-line QSL database for the 11&nbsp;meter / freebander community is QRZ11.COM, designed after its "big brother" [[QRZ.com]] for amateur radio.<ref>{{cite web |url=http://www.seas.upenn.edu/~uparc/documents/First%20Annual%20Official%20Wireless%20Blue%20Book%20-%201909.pdf |title=W3ABT – the Amateur Radio Club at the University of Pennsylvania |access-date=2009-06-19 |df=dmy-all |url-status=live |archive-url=https://web.archive.org/web/20100706002250/http://www.seas.upenn.edu/~uparc/documents/First%20Annual%20Official%20Wireless%20Blue%20Book%20-%201909.pdf |archive-date=2010-07-06}}</ref><ref>{{cite web |url=http://www.qrz11.com |title=QRZ11|website=www.qrz11.com |access-date=8 May 2018|url-status=live |archive-url=https://web.archive.org/web/20180223052034/http://www.qrz11.com/ |archive-date=23 February 2018}}</ref><ref>{{cite web |url=http://www.cq-amateur-radio.com/cq_highlights/2014_cq/2014_02_cq/CQ_2014_02_OPT.pdf |title=CQ 2014-02 OPT |access-date=2015-03-10 |url-status=live |archive-url=https://web.archive.org/web/20150215042512/http://www.cq-amateur-radio.com/cq_highlights/2014_cq/2014_02_cq/CQ_2014_02_OPT.pdf |archive-date=2015-02-15 }}</ref><ref>{{cite web |url=http://qrz11.phpbb8.de/download/file.php?id=44&sud=21333 |title=Archived copy |access-date=2015-03-10 |url-status=live |archive-url=https://web.archive.org/web/20150402103528/http://qrz11.phpbb8.de/download/file.php?id=44&sud=21333 |archive-date=2015-04-02 }}</ref><ref>{{cite web |url=http://www.dx27.net/viewpage.php?page_id=4 |title=www.dx27.net - QRZ Database |access-date=2015-03-10 |url-status=dead |archive-url=https://web.archive.org/web/20150402123935/http://www.dx27.net/viewpage.php?page_id=4 |archive-date=2015-04-02 |df=dmy-all}}</ref><ref>{{cite web |url=http://www.sugar-delta.it/site/index.php |title=Sugar Delta Home |place=Italy |website=Sugar-Delta.it |access-date=8 May 2018 |url-status=live |archive-url=https://web.archive.org/web/20170927214446/http://www.sugar-delta.it/site/index.php |archive-date=27 September 2017}}</ref>

== Media ==
During the 1970s and 1980s peak years of CB radio, many citizens band-themed magazines appeared on newsstands. Two magazines that dominated the time period were ''S9 CB Radio'' and ''CB Radio Magazine''. ''S9’''s successor was ''[[Popular Communications]]'', which had the same editor under a different publisher beginning in 1982. It covered hobby radio as well as CB. The same publisher produced a magazine called ''RADIO!'' for [[RadioShack]] stores in the mid-1990s. In Australia, ''CB Action Magazine'' was produced monthly from mid-1977 and continuing publication through until the early 1990s. ''CB Action'' spawned several other popular publications, including a communications and scanning magazine and ''Amateur Radio Action'' magazine, produced over several decades and running to some 18&nbsp;volumes.

In the early 2000s, ''[[National Communications Magazine]]'' added CB radio coverage to its coverage of [[Radio scanner|scanner radios]] and still remains the only magazine in [[North America]] covering CB radio.

==See also==
* [[Citizens Band radio in India]]
* [[List of CB slang]]

==Notes==
{{Notelist}}

==References==
{{Reflist|30em|refs=

<ref name=Kneitel1988>{{cite book |first=Tom |last=Kneitel |title=Tomcat's Big CB Handbook |publisher=CRB Research Books |location=Commack, New York |year=1988 |isbn=0-939780-07-0}}</ref>

<ref name=Chiltons1977>{{Cite book |last=Chilton Automotive Editorial Department |title=Chilton's CB Handbook |publisher=Chilton Book Company |location=Radnor, Pennsylvania |year=1977 |isbn=0-8019-6623-X}}</ref>
}}

{{Telecommunications}}
{{Two-way radio}}
{{Trucking industry in the United States}}
{{Authority control}}

[[Category:Citizens band radio| ]]
[[Category:1970s fads and trends]]
[[Category:Bandplans]]
[[Category:Radio hobbies]]
[[Category:Radio regulations]]