In their respective technical
control centers, each controller bears primary responsibility for the
send side of all circuits.
send side of all equipment.
receive side of all circuits.
receive side of all equipment.
The voice frequency primary patch bay interfaces the technical control
facility with the user circuits. In terms of signal flow, the user
circuits terminates on a
All high-level and nonstandard DC user circuits access the TCF through
the DC primary patch bay.
Circuits that are unbalanced to ground
enter through a primary patch designated as a