Each port may be attached to the boards or network/line cards via a SFP module which must be a OLT module for it to have its Tx and Rx wavelengths swapped, but not all OLTs use SFP modules as shown in the image to the left. 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 OLT is responsible not only for transmitting data from the core network to user terminals but also for managing bandwidth. An optical line termination (OLT), also called an optical line terminal, is a device which serves as the service provider endpoint of a passive optical network. In this guide, we'll demystify what an.