Wow seems like a good bit of people had bad experiences with phone interviews this admissions season.
I had two today, one with UT Austin and the other with Michigan. I wasn't grilled with any technical questions; in fact the only question I was asked was to describe one of my research projects. Then they told me about their research, the school, asked about my mathematical background/experience, my interests, etc. Everything was lighthearted, calm and respectable, and I never once felt like I was in the middle of an interview. One of the Professor's spent about 40 consecutive minutes talking about his research and problems he's interested in.
Both of them were pretty young (Ph.D. within the last 10 years), which probably had something to do with it.