Thus, a fiber termination box is used to terminate the optical fiber cables in the field and connect them to the pigtail by splicing. A fiber pigtail is a specific hardware connection used for cable termination. This guide will provide an in-depth. A Fiber Termination Box, also known as an optical termination box (OTB), is a compact, specialized enclosure designed for the organization, termination, splicing, and protection of fiber optic cables. In FTTH access networks, this type of enclosure.