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. What is the Fiber Termination Box? Fiber termination box (FTB), also known as optical terminal box (OTB). A fiber terminal box, also known as a fiber distribution box, is a device used in fiber-optic communication networks to terminate, splice, and distribute optical fibers. It aids in splicing, splitting, storing, and managing fibers within the appropriate.