Thus, a fiber termination box is used to terminate the optical fiber cables in the field and connect them to the pigtail by splicing. This cable type has a small diameter core, allowing only a single light mode to pass through it. Fiber patch cord: A fiber patch cord has connectors on both ends and is used to connect. 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. Fiber Optic Terminal. Serving as a critical connection point, FTB facilitates the termination, splicing, or connection of fibers from various cables to other network devices such as switches, routers, or Optical Network Terminals (ONTs).