Each cb radio setup has a max appoximate range of 5-6 mile radius from your location. Obstacles will obviously lower that, especialy inside a canyon. If someone has a cb radio say, 1 don't know, some 15 miles away, and his cb radio has a radius of about 5-6 miles with no obstacles, you will still miss him. Both of you would need to be within 11-12 miles apart. Basically, you need to be within each others radius to communicate. The closer you are to each other, the louder your cb radio gets.