🚀 go-pugleaf

It may have been fun to watch the guys trace your loop fault,
but it's really a lot of hard work to do it correctly.  The
buzzer was most likely the signal source on either a pair or on
a single wire (and ground) and the probe was an inductive
amplifier which is used to magnetically couple to the suspected
'good' wires.  Where the signal stops, the line is broken, not
unlike signal tracing in RF troubleshooting work.

By sweeping the antenna of the amplifier near the cable
containing your wire(s) they can listen for the distinctive
'tweedle' of the buzzer picked up from the magnetic emanations
of the electrical signal.

What's really bad is trying to do this while someone else in the
same building is doing the same thing! 

The butt set only helps to amplify the signal a bit.  Many units
come with the tiny speaker built right into the end of the probe.
This method is only a half-step up from a light bulb and a battery.

Many more sophisticated methods (obviously) exist, such as TDRM
(time-domain reflectrometry) which measures the impedence steps
using various standing waves and can detect opens, shorts, splits,
some types of bugs, connectors, etc. within a few feet.

The sky is the limit (pun) on telco diagnostic equipment these days.

"This document contains statements of opinion by the author
which are not attributable to BBN Communications Corporation or
its management."

Barry C. Nelson  / BBNCC Product Management/International Certifications