NO CB LICENSE REQUIRED!
ahhjaws,
The FCC placed the CB radio service into the Un licensed radio services category, under Part 15 of the Code of Federal Regulations. This is the main appeal of CB for offroading: Anyone can have a CB that allows them to communicate over a fairly good diatance, line of sight typically 5-15 miles, depending on terrain, band conditions, etc. This range allows you no only to communicate with others in a group on a trail run, but in case you get separated, have a breakdown, or other trouble, you can call for help. It is this reason that we require a working CB on the organized Serious Explorations trail runs like Truckhaven, Moab, Arizona, etc. We consider your CB to be essential SAFETY gear.
Unlike FRS, which has relatively short range, (which may be OK for communications in a relatively small group where you aren't too spread out), your CB is very "Universal" as almost all offroaders have them.
Years ago the FCC, inorder to comply with international communications treaties, did require you to "register" your radio and get a station license, good for your whole family. There was no exam, you had to pay only a small administration fee (about $10), and you were issued a callsign. such as "XXX1234"
The treaties were later re written, so callsigns aren't required for CB anymore.