The CB radio addon can be used to interact with the world.

It has a limited range and is only usable on a scout vehicle.

 

Some of the uses


Interact with a crane (making some cranes in harbors and other places usable)

This way you can load cargo in a waiting ship etc...  


Interact with a ferry point that is otherwise not usable, except with 

CB radio.  


Interact (with the locals) to find the location of a objective or upgrade 

that is otherwise not visible nor can be found on the map.


Interact to lower a bridge.  


Interact (with the power company) to get the current from the

downed power lines blocking the start of the mission to repair 

of the pylon.