I came across an old answer on this site which makes the claim:
It would take an act of Congress to change this [FCC Part 97] rule.
Is that correct? I was under the impression that United States Congress had delegated authority over civilian communications to the FCC.
Must Congress approve every change to Title 47, or does the FCC have the authority to determine those rules and regulations directly, as it sees fit (within its mandate)?
There are two different "Title 47"s in play here. Title 47 of the US Code, as referred to by rclocher3, contains laws passed by Congress on the subject of telecommunications. Most interesting for our purposes is Chapter 5, Subchapter 1 which establishes the FCC. It sets the compositon and appointment rules of the FCC, regulates how the FCC can spend money and how it can obtain revenue, and most importantly, in 47 USC 154(i), says that
The Commission may perform any and all acts, make such rules and regulations, and issue such orders, not inconsistent with this chapter, as may be necessary in the execution of its functions.
Which basically incorporates any rules the FCC makes as part of the law, given that they are within the purpose of the FCC as defined in the chapter preamble, and they don't conflict with the remainder of the law.
Those rules are cataloged and collected in Title 47 of the Code of Federal Regulations, which is what you linked to in your question. These are not established by acts of Congress, they're enabled by the act of congress that gives rulemaking power to the FCC. All of Part 97 is contained within 47 CFR. To change it, the FCC only needs to follow its own rules about how regulations are made. So you're correct about how the delegation works, and with few exceptions, it doesn't take an act of Congress. However, Congress can act by either passing a law mandating that the FCC takes a certain action, or by passing a law which directly overrides the FCC rules.
Most of the time that I have heard or read that statement: "It would take an act of Congress..." it is usually referring to an impossible or very difficult act.
However, the answer is "no" it does not take an act of congress to affect rule making or rules change within the FCC. Straight from the fcc.gov web site we have:
Most FCC rules are adopted by a process known as "notice and comment" rulemaking. Under that process, the FCC gives the public notice that it is considering adopting or modifying rules on a particular subject and seeks the public's comment. The Commission considers the comments in developing final rules.
However, congress can also pass laws that affect the FCC and may also result in rule changes. This usually happens when there is a subject or act that is in opposition to the politics and policies of the FCC or something that the FCC considers to be the responsibility of congress and not its own rulemaking facilities.
