The majority of radios that we supply come with the option of using CTCSS codes when transmitting. Many of our customers ask "what do these codes actually mean and what I should use them for? "
CTCSS is an acronym for Continuous Tone-coded Squelch System and is used to reduce the confusion that can be caused if there are many people in the same area that are transmitting on the same radio channel. This is particularly useful for radio users who may not want to hear other peoples conversations. Another useful function of CTCSS is that you can assign a CTCSS code to each of your departments or work groups.
CTCSS works by putting an audio tone that is too low pitched for people to hear over every transmission that you make. When another radio set to the same code picks up this noise it will decode the message. If the codes are different you will not hear the message. This has a practical effect of increasing the amount of people that can use the same frequency.
Other information.
- Set your CTCSS code to "0" to hear all transmissions on a channel.
- There are either 38 or 39 UK Standard CTCSS codes depending on your radio.
- If two different brands of radio do not talk to each other on the same code check the tone frequency in the manual to see if they are the same.
- There are at least 15 different CTCSS standards internationally!
- Brand names for CTCSS include: Selcall, private line, quiet channerl




