The ONU/ONT is the final network boundary—the device that transforms the high-speed optical signal back into standard electrical interfaces (Ethernet, Wi-Fi, POTS) usable by the customer's devices. An Optical Distribution Network is a passive optical transmission system composed of optical fibers, splitters, distribution frames, and connectors. In FTTH, FTTB, and other fiber access networks, terms such as Fiber Optic Termination Box, Fiber Distribution Box (FDB), and ODF (Optical Distribution Frame) are frequently mentioned. It's where incoming and outgoing cables meet. It does four key things: Think of it as the central hub for your fiber network.