It's organized by components, but some section headers (like "Stuck sender") are not clearly components. Fix this.
Add more section headers when needed.
My edits to add "Telephone numbering" etc. introduce useful background information, but need to be reorganized.
Make my style match the original.
Expand abbreviations like SXS.
Try to introduce concepts/terms in only one place, as early as possible.
See copy/move notes in next section.
If current polarity is only used for synchronization, it doesn't carry information; thus I believe the comment about bit-to-baud ratio is wrong. Check with other people.
Check titles and page numbers (or URLs) cited. Add links to references, or citations.
Needs background information. When was it invented? Who invented it, AT&T or another organization? How long was it used? Which other types of equipment work with it? Specific people, dates, etc.?
Clarify that it was invented to work in the US, so it is tied into the US numbering and office organization system. Be brief, however.
Need picture of a call indicator. Encoder might be interesting. Other pictures might be interesting.
Write examples. Cases: 4 digits, 4 digits + party, 5 digits. If possible, use real Seattle numbers.
Scan of part of a phone book page showing party line entries, or manual office line numbers >10000, would be interesting.
Copy or move information about sending 7 digits (used in tandem offices) from Panel office. I need more information about # digits and encoding as they evolved over the years. Sending to a call indicator is not the same as sending to a register in a tandem office.
Correct, then copy or move information about bit-to-baud ratio from Panel office.
Explain meanings of names for digit "slots", particularly Stations. A "station" = an individual telephone = an individual telephone in a party line, but the stations digit is also used for ten-thousands.
Or perhaps remove the word "stations" from the table.
Add information about the heavy positive pulse (at time 17) once I understand it.
Find schematics and add information about how unused combinations are decoded? It may have changed over the years.
Consider using background color to distinguish 0 from 1 bits, since that's more important than polarity.
Ask blind users about Braille and speech accessibility.
I couldn't figure out how to use nested tables, but it may still be possible.
Add a link from "PCI" page.
Check titles and page numbers (or URLs) cited. Add links to references, or citations.