[Panel] How does the line finder work?
41:36
Why isn't the 1XB completing calls?
35:12
How does a No. 1 Crossbar work? - Dial Equipment Appreciation, Part 2
16:34
Booting up the 3ESS
43:15
[Panel] Sarah troubleshoots Incoming #30
27:08
At the Connections Museum: the insane telephone technology that led to today's computers
24:03
[5XB] Bob tells a story about barging in on someone's line.
26:27
The 5XB Trouble Recorder
35:35