Two-way radios have a limited number of channels available based on
the frequencies assigned by the FCC, so there is always a chance someone
else may be using the same channel you are using. This is the reason for
Privacy codes are based on the
DCS codes capability of two-way radios. A receiving radio that has a
privacy code set will not un-mute its speaker unless that code is sent
along with a transmission.
So if a receiving radio is set to channel 2 and privacy code 5. The
transmitting radio must be set to the same channel and code. This way
you will be able to communicate between two radios without interference.
You can also have a select group set to the same channel and code to
effectively communicate with a group of users at the same time.
But, it should be understood that the privacy codes, as such, do not
ensure privacy of your conversation. If any unknown user tunes in to the
same channel and code that you are using, he or she can listen to the
conversation taking place. So, the privacy codes feature should be
looked at more as a interference eliminator rather than a feature that
provides privacy of conversation.
One of the downsides of
privacy codes is that you could assume that
since you do not hear any communication on your radio, the channel is
not being used. Then when you press the Talk button on your radio and
start talking, you will be talking over the person who is already
transmitting. If this occurs all transmissions for all radios will be
garbled. Most 2-way radios have a Monitor button that disables the
privacy code feature while the button is pressed so you can hear if
there is any activity on the channel before you transmit.