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Use this channel to connect your Rasa assistant to Twilio Media Streams for voice capabilities. Unlike the standard Twilio Voice connector, this channel handles speech-to-text (ASR) and text-to-speech (TTS) processing directly in Rasa.

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Configuring Twilio Webhook

Bot URLs for developmentVisit this section to learn how to generate the required bot URL when testing the channel on your local machine.
Go to the Phone Numbers section of your Twilio account and select the phone number you want to connect to Rasa.
Select the option “Webhook, TwiML Bin, Function, Studio Flow, Proxy Service” and set the URL of your Rasa Server as webhook. Depending on the hostname, the webhook URL would be
Your webhook endpoint must be served over HTTPS. Twilio Media Streams does not accept insecure HTTP URLs. Screenshot of Twilio Console to Set Webhook

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Using Basic Authentication

Basic AuthenticationRasa supports Basic Authentication for Twilio Media Streams in Rasa Pro 3.11.8+, Rasa Pro 3.12.7+ and latest releases.
If you want to use basic authentication for your Twilio Media Streams channel, you need to set the webhook URL in the following format:
For more info checkout the Twilio security documentation.

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Basic Rasa Configuration

Create or edit your credentials.yml and add the following channel configuration:
credentials.yml
Basic AuthenticationSupport for username and password parameters is available in Rasa Pro 3.11.8+, Rasa Pro 3.12.7+ and latest releases.
Twilio Media Streams channel configuration expects the following parameters:
  • server_url (required): The domain at which Rasa server is available. Do not include protocol (ws:// or wss://). For example, if your server is deployed on https://example.ngrok.app, server_url should be example.ngrok.app.
  • asr (required): Configuration for Automatic Speech Recognition. See Speech Integrations for a list of ASR engines for which Rasa provides built-in integration with.
  • tts (required): Configuration for Text-To-Speech. See Speech Integrations for a list of TTS engines for which Rasa provides built-in integration with.
  • username (optional): Basic authentication username for Twilio Media Streams channel.
  • password (optional): Basic authentication password for Twilio Media Streams channel.
  • interruptions (optional): Configuration for interruption handling. This allows the assistant to detect when users interrupt while the assistant is speaking and respond more naturally. See Interruption Handling for more information.
Check using basic authentication on how to setup Twilio webhook with basic authentication. You can run the assistant using the command rasa run. You’ll need a URL accessible by Twilio for your Rasa assistant. For development, you can use tools like ngrok or Cloudflare Tunnel. You can also run it with a development inspector using rasa run --inspect. To see all available parameters for this command, use rasa run -h.

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Usage

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Receiving Audio

When a user speaks, Twilio streams the audio to Rasa where:
  1. The audio stream is collected and buffered
  2. The configured ASR service converts speech to text
  3. The text is processed by Rasa’s NLU pipeline

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Sending Responses

For bot responses:
  1. Rasa generates text responses
  2. The configured TTS service converts text to audio
  3. Audio is streamed back to Twilio

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Call Events

Like other voice channels, the following events are supported:

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Call Metadata

Metadata about the call can be accessed by the slot session_started_metadata in the beginning of the call. Following fields are available: A custom action_session_start can be used to store this information to a slot.