In both cases, the speech recognition works well. A major source of errors in dictation software is the computer's poor ability to use context to understand what you mean to say and convert thousands of words into precise text. But phone-based systems need to understand only a few keywords. Once you say ''traffic,'' they then know that any subsequent request concerns traffic conditions, not movies or stock quotes, vastly improving accuracy. There are three technologies for getting information back out.
Synthesized speech takes text and automatically but imperfectly converts it to spoken language.
The result is full of odd inflections and can be hard to understand. Sampling assembles language from snippets of human speech, producing a sort of audio ransom note, with different words or phrases read by different voices. The most natural, but least flexible, approach is to select responses from recorded scripts. Both Tellme and Quack employ mixtures of these methods, but Tellme mostly uses canned recordings, while Quack uses a lot of sampling, which makes it harder to understand. Overall, I found Tellme more appealing.