OLT is the starting point for the passive optical network, which is connected to a core switch through Ethernet cables. In the age of fiber-to-the-home (FTTH) and ultra-broadband connectivity, the Optical Line Terminal - or OLT - is one of the most crucial devices powering our high-speed digital world. The primary role of an OLT is to convert, frame, and transmit signals for the PON network. Copyright © 1981, Regents of the University of California.