In Fiber to the Home (FTTH) networks OLT stands for Optical Line Terminal.
>OLT is the starting point for the passive optical network, which is connected to a upstream core network.
>The OLT convert, frame, and transmit signals for the PON network and to coordinate the optical network terminals.
>PON works on wavelength division multiplexing using one wavelength for downstream traffic and one wavelength for upstream traffic on a single fiber. Both EPON and GPON operate similarly since they are a type of PON, but there are differences.