If you're responding to me, directly, as a network/VoIP engineer, I'm very well aware of your point however I was providing the OP "real world" experiences, so a more informed decision can be made.

"Data rates" for Edge should be more than sufficient to handle a VoIP call, but again, the quality of signal doesn't seem up to snuff on AT&T, at least in my area (Balt/DC corridor).

To me 3G/3.5G is only slightly faster than 2G/2.5G, so it's not a deal breaker. Whether 3G or 2G I try to keep the amount of data as low as absolutely possible, because there's cost/megabyte to take into account.