The Federal Communications Commission regulates all radio activity in the United States. In addition to granting amateur radio licenses, they also auction off spectrum rights, work with experimental radio equipment, and regular radio and TV stations.
If you get a ham radio license, at some point you’ll need to deal with the FCC. You do this via the Universal Licensing System, or ULS. You can find the ULS here:
Anyone who interacts with the FCC needs an FCC Registration Number, or FRN. If you already have your ham license, you have an FRN (and, most likely, you’re probably not interested in this post). If you’re thinking of getting a ham license, the FCC recommends that you get your FRN before taking your exam. This will allow them to easily match up your exam results with the rest of your information (name, address, phone number, and Social Security number1).
Moreover, there’s usually 5-10 days between the time you take your exam and when your license is issued (assuming that you pass). During that time, you will be on pins and needles waiting to here what your new call sign will be. Having an FRN will allow you to login to the ULS and check your license status.
the FCC, like most other government agencies, is required to collect your SSN, not because they use it to identify you, but so that the IRS and other agencies can track you down if you owe taxes or child support. ↩︎