Twilio Media Streams | Rasa Documentation

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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.

Configuring Twilio Webhook

Bot URLs for development

Visit 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

https://yourdomain.com/webhooks/twilio_media_streams/webhook

Your webhook endpoint must be served over HTTPS. Twilio Media Streams does not accept insecure HTTP URLs.

Using Basic Authentication

Basic Authentication

Rasa 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:

https://<username>:<password>@yourdomain.com/webhooks/twilio_media_streams/webhook

For more info checkout the Twilio security documentation.

Basic Rasa Configuration

Create or edit your credentials.yml and add the following channel configuration:

credentials.yml

twilio_media_streams:
  server_url: "<your-domain>"
  # ASR Configuration
  asr:
    name: "azure"  # or "deepgram"
    # Add ASR-specific configuration here

# TTS Configuration
  tts:
    name: "azure"  # or "cartesia"
    # Add TTS-specific configuration here

# Basic Authentication
  username: "<username>"
  password: "<password>"

Basic Authentication

Support 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.

Usage

Receiving Audio

When a user speaks, Twilio streams the audio to Rasa where:

The audio stream is collected and buffered
The configured ASR service converts speech to text
The text is processed by Rasa's NLU pipeline

Sending Responses

For bot responses:

Rasa generates text responses
The configured TTS service converts text to audio
Audio is streamed back to Twilio

Call Events

Like other voice channels, the following events are supported:

Event	Intent	Description
`start`	`session_start`	Triggered when call connects
`end`	`session_end`	Triggered when call disconnects
`DTMF`	-	Phone keypad presses (sent as text messages)

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:

Field Name	Description	Source
`call_id`	The unique call identifier from Twilio	`call_id` parameter as sent by Twilio
`user_phone`	The phone number of the user	`user_phone` parameter
`bot_phone`	The phone number of the bot	`bot_phone` parameter
`direction`	The call direction	`direction` parameter
`stream_id`	The unique stream identifier	`streamSid` from Twilio Media Streams

A custom action_session_start can be used to store this information to a slot.