Fiber-optic communication.

In the backward 1970s and aboriginal 1980s the arrangement was bent to be bombastic with the beforehand of digital and fiber-optic communication. A few cables were upgraded to T-4 and T-5 instead of L-5, but a lot of were never upgraded accomplished L-4 due to advance of technology. Generally, the advance of bottle cilia and laser technology fabricated chestnut coaxial cable anachronistic for all continued booty carrier service, as Western Electric had assuredly fielded the FT Series G single-mode cilia cable arrangement by 1984.5