Guide to North American Switches
Here's something I've been working on for a bit. What draws me into phones the most is switching equipment, so I've been trying to write a definitive guide to what makes them weird, different, and how they can enable certain privileges you don't otherwise have. Like any good document, it doesn't just talk about a lot of these things, but gives you the ability to experience as much of them yourself as possible. Every section has numbers you can call associated with a type of switch. I've set it down over the course of the last couple months, but will update it at some point. Enjoy though, and let me know if you have any feedback or suggestions.
EDIT: I made a few minor changes to the document, mostly to reflect that some 5ESSes do in fact let you use the 0110 CAC. This is a relatively new discovery, so any sort of unorthodox input it can accept is still being researched.