Unlike indoor setups, you can't afford to use generic or under-specified cable outdoors. The right choice reduces signal loss, prevents downtime, and avoids expensive repairs or replacements. Fibers sit loosely inside gel-filled tubes that block moisture and buffer thermal. UV exposure, water ingress, rodents, ice, crushing pressure—cables must survive it all. Fibers sit loosely. This guide covers how to safeguard outdoor fiber optics across underground, aerial, direct-burial, and exposed setups. Indoor fiber optic cables are commonly used in buildings, offices. The center of a fiber optic cable is a thin glass tube called the core, which moves the light pulses. It may be a single-mode or multimode core. The coating around that is a buffer to absorb shocks.