We have it working using the web hooks. We use web hooks to send us notifications on (1) ring; (2) answer; (3) recording complete and (4) transcription complete. Lots of good data that gets poked into our SQL database. On the recording complete post, it includes an URL for the recording file, so we do a second call and insert the recording into our database too.
We wrote a generic handler on our end that the webhook posts too.
Dan