Ignore my previous entries about SkypeIn. My SkypeIn number is working fine. It was user error.
I had the last two digits of my number transposed. The first few times I tested it, I dialed the number correctly. After that I got the last 2 digits confused, and I’ve been dialing that (incorrect) number since.
Open mouth, insert boot. Proceed to jam boot down throat.
Sigh.