I've been hackin' around the Skype API, tinkering mostly, but thinking about some dev stuff.
Found a section explaining what pretty much every error message means that you could possibly encounter.
I've chosen 15 of the most common Skype user gotchas. Here they are, by number error name, and my explanation.
5- Search CALLS: invalid target. You used a non-permitted character, such as a number (i.e., tic-tac-toe sign).
9- Unknown user. That one is pretty obvious.
22- Cannot hold this call at the moment. Trying to place a call on hold when the call is not actually taking place. Stay away from the funny stuff, bud.
23-Cannot resume this call at the moment. Like duh. You can't resume a call if there is no call underway.
24- Cannot hangup interactive call. Sense a pattern here?
35- Not connected. Useful if you think you are talking to someone over Skype, but you actually are not connected to them. Gotta tell ya, has happened to me more than once. U-too?
36- Not online. If you have your Skype UI up, but then your Internet access goes down, well you get the picture.
39- user blocked. It could be that the person you are calling has caller ID that only lets known numbers through. Before I got SkypeIn, this was a problem, because the source phone number showed as a European, multi-digit code that caller I.D systems are probably not gonna git.
66- Not connected. In this case, means that you are logged out of Skype.
91- Call error. This is given if you cannot reach an emergency number. Interesting to see if the FCC E911 ruling will apply here. What's the frequency, Kevin? (Martin, FCC chair)
92- Call error. You'll get this if you try to call a non-valid traditional phone number.
94- Call error. You'll get this if you try to call yourself. Why would anyone want to call themself when it is so easy to just talk to yourself offline? Take it from someone who knows :-)
105- Invalid chat name. This happens if you try to start a Skype IM chat without indicating the name of the chat participant.
500- CHAT: Invalid chat name given. Phoo on you for starting a Skype chat by typing in "sax kitten," if ya know what I mean.
and finally (grrrr)
9901-Internal error. Skype's way of saying it's their fault, not yours.
They've admitted it. Cherish the moment.