I've got a phone screen with MSFT tomorrow for the developer gig. I absolutely dread these things. The problem is that they come in three varieties. The first tests your knowledge on conceptual stuff and basic understanding of common stuff you need for the platform your work on. These aren't bad, and these are I think the kind of thing that you're supposed to look for in a phone screen. I've been on both sides of those conversations, and they're the right way to sniff out a phony.
On the other hand, some people try to test to see if you have an encyclopedic knowledge of a framework, and those suck. I don't know every property of every class in the framework, but I can Google it and get the job done just like the next guy. I would never ask a potential hire these kinds of questions, because stumping them is not something I'm interested in.
Then there's the ultimate computer science nerd screen, which is worse than the encyclopedic screen. No, I have not read the GoF design pattern book, and likely never will. So if you ask me about the most rarely used patterns, I won't know what to tell you. But ask me about every day things like dependency injection and factories and such and I'll explain them and give examples.
So I'm crossing my fingers for the first scenario, but you just never know. I really need to get back to work. I can't stand being home all of the time and talking to cats.