I work for a Telco and we implemented speech driven self service. Our subscribers HATED it - they found every possible path into the organisation, as long as they could avoid the speech driven one. The speech reco camp have been punting speech as the next best thing for years, trying to convince us about how it learns as you get more input into the engine. The bottom line is....it sucks, it doesn't work, and is extremely dialect specific. Just another bullet point on the feature list.