Article I wrote for Radio and Communications magazine in 1999

At that time UHF CB had 40 wideband channels and sub-audible tones were not permitted on the band. The regulator of the day was known as the Australian Communications Authority.

The band was very busy with many users in those days, over the years it grew in popularity with hobbyists and commercial users and many arguments ensued with some commercial users claiming a channel as their own.

Finally on May 27, 2011 the Australian Communications and Media Authority (ACMA) expanded the band to 80 channels by reducing channel spacing from 25 kHz to 12.5 kHz narrowband to double the capacity without increasing the overall frequency band width.

40 new channels (41 to 80) were interleaved right between the original 40 channels. 41 sits between the original channels 1 and 2.

The expansion effectively provides 77 usable channels, as channels 61, 62, and 63 are reserved due to data channels 22 and 23 retaining a wider 25 kHz bandwidth.

Sub audible tones known as CTCSS and DCS also became legal on the band after commercial interests pushed for the 80 channels and tones to cater for their customers.