FMCSA operating authority is often identified as an "MC," "FF," or "MX" number, depending on the type of authority that is granted. If you do not have access to the internet you can call the FMCSA toll free number 1-800-832-5660 to request a form be mailed to you.Apply for your trucking authority. You will first need to complete and submit a Registration Form that can be found on our website. Your company will need to be registered with the state of Utah. The operating authority letter contains pertinent details about a carrier or driver and what they can legally do within the commercial trucking industry. If you have questions about starting a trucking company or want to know about Motor Carrier HQ, check out some of our frequently asked questions. If you have questions about starting a trucking company or want to know about Motor Carrier HQ, check out some of our frequently asked questions. OUT-OF-SERVICE: Carrier is under any type of out-of-service order and is not authorized to operate. Operating Authority Status.