What does the FCC code RJ refer to?

The FCC code "RJ" stands for "Registered Jack," which is a standardized telecommunications interface used for connecting various communication devices. Registered Jacks are defined by the Federal Communications Commission (FCC) to facilitate interoperability between different types of telecommunications equipment.

The designation "RJ" is followed by a number that specifies the particular wiring configuration and pinout used for that connection. For example, RJ11 is commonly used for telephone lines and consists of a standard 6-position connector, while RJ45 is typically used for Ethernet networking with an 8-position connector.

Understanding that "Registered Jack" refers specifically to these standardized interfaces helps clarify the significance of RJ codes in telecommunications, as they ensure compatibility and proper function across different devices and systems. The other options, while related to types of jacks or connectors, do not accurately define the FCC code RJ.