@ChadBeeder Re-watched that part a few times. At first I though you had left that breakpoint disabled but that doesn't seem to be the case. Perhaps the modem wasn't powered on in the first place and that function is never called?
Anyway I'll be checking back to see if someone figures it out.
The link to part one under the "More episodes in this show" section of this page doesn't work. There's probably some HTML escaping bug involved as the angle brackets are not displayed correctly in the link text.
Regarding Erik's remark at the end: With explicit state management you can easily check the state of a phone call in the database. But if you try to inspect a serialized continuation you would see something like a line number and a stack trace. That may be great for debugging but it could make it harder to tweak the code or database before the operation terminates. The current trend in web development is to be very explicit about state. But maybe we're pushing it too far, I don't know.