http://developer.att.com/apis/speech
Twilio has one that also requires payment:
https://www.twilio.com/docs/api/rest/transcription
It limits input audio to 2 minutes. And I would have to guess that its model is specifically tuned to phone messages, i.e. one speaker, relatively clear and focused audio, and certain probabilities of phrases.
http://developer.att.com/apis/speech
Twilio has one that also requires payment:
https://www.twilio.com/docs/api/rest/transcription
It limits input audio to 2 minutes. And I would have to guess that its model is specifically tuned to phone messages, i.e. one speaker, relatively clear and focused audio, and certain probabilities of phrases.