This document summarizes two key components of optical fiber communication networks: the optical line terminator and optical network terminals. The optical line terminator serves as the service provider endpoint, performing conversions between electrical and fiber optic signals and coordinating multiplexing. It can transmit data to 128 optical network terminals within a 12.5 mile range using optical splitters. Optical network terminals terminate fiber optic lines at customer premises, demultiplexing signals and providing power for telephones and other devices. Many optical network terminals have battery backups to maintain service during power outages.