Leaving the Central Office are several cables of several hundred pairs.
They normally are placed in concrete ducts buried underground -- hence
the name, "underground cable". The Underground is also know as the
F1 cable. The cable is actually several pieces of cable, spliced
together in manholes. At some manholes pairs are tapped and run up
into a B-Box where they are cross-connected to aerial cables (aka F2
cables.) Office buildings and larger apartment buildings may have
a terminal connected to the F1. The aerial cable is spliced into
aerial terminals where pairs may be tied to a drop wire. The drop
wire drops from the aerial terminal to the protector on the customer's
Pictuires to come: Inside a Manhole, The B-Box, Aerial cable,
Terminals (aerial and buried), Protectors and NIDs.