RE: Quick circuit question.

Just to be accurate, DS is digital service cross connect
i.e. dsx1 panel, dsx3 panel, etc. Typically a ds0 cross connect is
referred to as "ds0 wire frame" since it's muxed up to ds1's via
DSX1 bays.

A DSX panel is basically a piece of dumb equipment, sometimes fitted
with led port tracers(useful)that you can configure in interconnect, one
card, or cross connect, two card, modes for testing both sides, good add
move, drop capability, etc.