Returns a previously submitted speech recognition task by its id. Once the task has succeeded result holds the transcription; until then it is not yet populated, so the method can be polled until it is. Depending on the task type the response also contains a call summary and a call score with its description. Only tasks of the authenticated customer can be read; any other id returns 404. A recognition token of the authenticated account may be passed in the X-Recognition-Token header (or as a token query parameter); API keys allowed to use Speech Recognition may omit it.