Usually the walkie-talkie can be programmed to change or set its own parameters (such as frequency or CTCSS). And the walkie-talkie without a keyboard needs to be programmed by connecting a computer through a programming cable.
For example the Retevis RT21. Here are 2 ways about programming:
1. You could download the software from our website: http://www.retevis.com/resources-center/ , please use the “USB Universal Driver”.
1) Please kindly install the programming software and USB driver to your computer. (The files are not compatible with MAC )
2) Open the software, and use the programming cable to connect a radio with computer, the radio need keep power on, also you need to choose the correct port. If you do not know which port is correct, you could try it one by one
3)Then the Program and choose Read from Radio, all the settings will be shown on the screen, then you will be able to reset it as you like.
4) Click the Program, and choose Write to Radio will be OK
5) Remove the radio and connect other one, keep the radio power on
6) Click the Program, and choose Write Data to Radio will be reprogrammed to the same settings with the first radio.
When you use this method to program the radio, the first time you need to install the driver and programming software, which looks complicated but simple to use. But the next time you use it, it will simpler.
Note: the driver coming with radio only support window XP/ Window 7 /Window 8/Window 10
2.You can use the chirp to programming. Go to this website: http://chirp.danplanet.com/projects/chirp/wiki/Download
Windows users will want the installer.exe file
MacOS users will want the app.zip file (and also need the runtime)
Linux users may want the tar.gz file (but Ubuntu users should use the PPA)
1)After you download the file, install it, and find the right port and correct model for your radio. If you don’t know how to find the correct port, please try it one by one.
2) Click the Radio, then choose the correct model of your radio.
3)After that you are able to programming the radio.
When you use the Chirp to program the radio, you do not need the driver. This way is more convenient.
The programming can modify the original frequency of the walkie-talkie and then write the modified frequency. So the programming of the walkie-talkie is a very convenient and simple operation.
Video connection for your reference：