This blog post describes how SignalWire developers should integrate with Voicegain Speech-to-Text/ASR based on the application that they are building.

Voicegain offers a highly accurate Speech-to-Text/ASR option on SignalWire. Voicegain is  very disruptively priced and one of the main benefits is that it allows developers to customize the underlying acoustic models to achieve very high accuracy for specific accents or industry verticals.

#1:  Real-time Transcription and Speech Analytics using LaML <Stream>

SignalWire developers can fork audio to Voicegain using the <Stream> instruction in LAML. The <Stream> instruction makes it possible to send raw audio streams from a running phone call over WebSockets in near real time, to a specified URL.

Developers looking to just get the raw text/transcript may use the Voicegain STT API to get real time transcription of streamed audio from SignalWire.

For developers that need NLU tags like sentiment, named entities, intents and keywords in addition to the transcript, Voicegain's Speech Analytics API provides those metrics in addition to the transcript.

Applications of real-time transcription and speech analytics include live agent assist in contact centers, extraction of insights for sales calls conducted over telephony, and meeting analytics.

#2: Voice Bot or Directed Dialog Speech IVR

If you want to build a Voice Bot or a directed dialog Speech IVR application that handles calls coming over SignalWire then we suggest using Voicegain Telephony Bot API. This is a web callback API similar to LaML and has instructions or  commands specifically helpful in building IVRs or Voice Bots. This API handles speech-to-text, DTMF digits and also plays prompts (TTS, pre-recorded, or a combination).

Your calls are transferred from SignalWire to a Voicegain provided SIP endpoint (based on FreeSWITCH) using a simple SIP INVITE.

Voicegain Telephony Bot API allows you to build two types of applications:

• Voice Bot applications using a Bot framework of your choice. The "ear" and "mouth" of the bot is provided by Voicegain where as the Bot Framework manages the dialog and extracts intents from the transcribed text. This blog post describes how you can build a Voice Bot using the RASA Bot Framework.
  

• Directed Dialog IVRs using call flows and grammars. You can either program them directly using Telephony Bot API by implementing appropriate callbacks. Alternatively, we provide a simple script that allows you to specify the entire IVR application in a declarative way in a YAML file. You can find a complete example how to do this on our github: platform/declarative-ivr at master · voicegain/platform (github.com)
  

#3: Custom Applications  

If your application has only a limited need for speech recognition, you can invoke Voicegain STT API only as needed. Every time you need speech recognition in your application, you can simply start a new ASR session with Voicegain either in transcribe (large vocabulary transcription) or recognize (grammar-based recognition) mode. You can use the LAML <stream> command

An example application that could be a voice controlled voicemail retrieval  or dictation application where Voicegain recognize API is used in a continuous mode and listens to commands like play, stop, next, etc.

In addition to SignalWire, Voicegain also offers integrations with FreeSWITCH using the built-in mrcp plug-in and a separate module for real-time transcription.

If you are a developer on SignalWire and would like to build an app that requires Speech-to-Text/ASR, you can sign up for a developer account using the instructions provided here.