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 MHz.

By the mid-1970s, hobbyists were experimenting with handheld radios and unauthorized 23 channel American CB radios. At that time in Australia, licensed ham operators and Emergency Services still used the 11-meter band which was not yet available for CB use. Multiple CB clubs had formed by this time, which assigned call signs to members, exchanged QSL cards, and lobbied for the legalisation of CB. In late 1977, having legalised Australian CB and allowed the import/sale of American and Japanese 23 channel sets, the Federal Government drafted new interim regulations for Australian 18 channel transceivers. The new RB249 regulations came into effect on January 1, 1978, and the last official registration date for 23 channel sets was January 31, 1978. After this date, the use of unregistered 23 channel CB sets was deemed illegal and unlicensed sets were no longer eligible to be licensed. The 18 channel band plan used 16 channels of the 23 channel CB radios plus 2 extra channels at 27.095 and 27.195 MHz, to make up the 18 channels. The original channels 1, 2, 3, 4, 10, 21, and 23 were deleted from the 18 channel band plan. So channel 1 on an 18 channel was actually channel 5 on a 23 channel radio. These roughly correspond to the present channels 5–22, except for the two unique frequencies that are known as 11A (Channel 7 on an 18 channel Australian CB) and 19A (Channel 16 on an 18 channel Australian CB) or remote control frequencies but are no longer part of the Australian 27 MHz CB band since 40 Channels were introduced. On January 1, 1982, the American 40 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 licences were issued (Australia's Population in 1978 was 14.36 million). The regulations called for one licence per CB radio. The price for a licence in 1977 was AU$25 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 MHz, allowed output power being 4 Watts AM and 12 Watts SSB. When UHF CB was first legalised the 27 MHz CB Band was intended to be closed to Australian CBers in 1982 and only the 477 MHz UHF band was to continue, but this did not eventuate. The first 477 MHz CB radio in 1977 was designed and made in Australia by Philips and was a 40 channel CB called the FM320.