TwiML™ Voice: <VirtualAgent> with Dialogflow CX

Before using <VirtualAgent>, you must complete the Dialogflow CX one-click integration.

<VirtualAgent> is a TwiML noun that is nested within the <Connect> verb.

<Connect>'s action and method attributes allow you to execute a new set of TwiML instructions for a call after the <Connect><VirtualAgent> session ends.

The action attribute takes an absolute or relative URL as a value. After a <Connect><VirtualAgent> session ends, Twilio will send an HTTP request to this action URL and will expect a new set of TwiML instructions in the response. If you do not provide an action attribute, Twilio will request TwiML from the current TwiML document.

The following code sample is an example of using the action attribute with <Connect> and <VirtualAgent>.

1
const VoiceResponse = require('twilio').twiml.VoiceResponse;
2

3
const response = new VoiceResponse();
4
const connect = response.connect({
5
    action: 'https://myactionurl.com/twiml'
6
});
7
connect.virtualAgent({
8
    connectorName: 'project',
9
    statusCallback: 'https://mycallbackurl.com'
10
});
11

12
console.log(response.toString());

1
<?xml version="1.0" encoding="UTF-8"?>
2
<Response>
3
  <Connect action="https://myactionurl.com/twiml" >
4
    <VirtualAgent connectorName="project" statusCallback="https://mycallbackurl.com"/>
5
  </Connect>
6
</Response>

For Dialogflow CX, this HTTP request's body will contain additional information about the result of the <Connect><VirtualAgent> session, along with Twilio's standard request parameters. A <Connect><VirtualAgent> session ends (and thereby triggers Twilio's HTTP request to the action URL) in the following ways:

• The Dialogflow CX agent session ends successfully and the caller did not hang up
• The conversation with the Dialogflow CX agent requires a live agent handoff
• The caller hangs up
• An error occurred during the VirtualAgent session

The body of Twilio's request to the action URL contains properties about the <Connect><VirtualAgent> session, along with Twilio's standard request parameters. You can use this information to configure the call behavior after a <Connect><VirtualAgent> session, or to log information for analytics purposes.

This property describes why the VirtualAgent session ended. Possible values are:

• completed: VirtualAgent session was terminated by one of the following:
  • The Dialogflow CX agent indicated end of conversation (by matching the end of conversation intent)
  • The caller hung up
• live-agent-handoff: VirtualAgent returned a live agent handoff response
• failed: An error occurred during VirtualAgent processing
• paused: VirtualAgent session was paused with the intention of the session being resumed later

This property is a JSON string containing Dialogflow-specific data from the agent interaction:

• ConversationId: Unique identifier for this conversation provided by Google
• EndUserId: Unique identifier for the end user participant provided by Google
• AgentHandoffParameters: Parameters included from the Dialogflow CX agent if the agent returned a live agent handoff response
• PauseParameters: Custom parameters included from the Dialogflow CX agent if the agent returned a custom payload response with "TWILIO_ACTION": "PAUSE".

If you want a call to continue after a <Connect><VirtualAgent> session ends, your application should provide new TwiML instructions based on the <Connect><VirtualAgent> session.

This optional <Connect> attribute indicates the HTTP request method to be used when Twilio sends a request to the action URL. If you don't specify a method attribute in <Connect>, POST is used by default.

The allowed values are POST and GET.

The table below lists all of the <VirtualAgent> attributes with their allowed values. The Dialogflow CX integration allows additional customization of the call flow using <Parameter> and <Configuration> TwiML nouns.

The connectorName is a string, configured in Dialogflow CX connector instance in the Unique Name field. You can review your Dialogflow CX connector instances in the Twilio Console.

The statusCallback attribute is an absolute URL where Twilio will send HTTP requests. While the Dialogflow agent interaction is in progress, Twilio will send HTTP requests to this URL each time an intent matches in the Dialogflow agent's conversation.

The body of Twilio's requests to your statusCallback URL contains information about intents, transcripts (caller text vs. virtual agent text), sentiment analysis (if enabled), and custom parameters that were sent to Dialogflow to build custom logic.

The body of Twilio's request to your statusCallback URL contains the following properties:

This parameter in the status callback is a JSON string containing the Dialogflow CX-specific intent event data. The JSON string can contain the following fields:

This is the HTTP method to use when requesting the statusCallback URL. Accepted values are GET or POST, and the default value is POST.

You can pass custom key-value pairs to your Dialogflow CX agent by using the nested <Parameter> TwiML noun within <VirtualAgent>. The <Parameter> noun allows you to send custom session parameters to your Dialogflow CX virtual agent, which can be referenced in your agent as $session.params.parameter-name.

<Parameter> has two attributes: name and value, both of which must be used every time you use <Parameter>.

For example, if you want to provide the end caller with a personalized agent greeting, you can supply a nested <Parameter> element with the customer name to the Dialogflow CX agent as in the following code sample.

This key-value pair will be passed in as a session parameter which can be referenced under $session.params.cutomer_name at runtime in your Dialogflow CX agent.

1
const VoiceResponse = require('twilio').twiml.VoiceResponse;
2

3
const response = new VoiceResponse();
4
const connect = response.connect();
5
const virtualagent = connect.virtualAgent({connectorName: 'uniqueName'});
6
virtualagent.parameter({name: 'customer_name', value: 'Burton Guster'});
7

8
console.log(response.toString());

1
<Response>
2
  <Connect>
3
    <VirtualAgent connectorName="uniqueName">
4
      <Parameter name="customer_name" value="Burton Guster"/>
5
    </VirtualAgent>
6
  </Connect>
7
</Response>

You can pause and resume a Dialogflow CX agent conversation session at any time. This allows you to pass a call back and forth between Dialogflow and Twilio while keeping the session context intact. As a result, the caller doesn't need to repeat themselves or start from the beginning when the call is passed back to Dialogflow.

Note that sessions have a 30 minute TTL (time-to-live) for inactivity between pausing and resuming.

To pause a session, your Dialogflow CX agent must return a custom payload JSON response that contains the key TWILIO_ACTION with the value PAUSE. This signals to Twilio that the session should be paused. Twilio then sends a request to the action URL you've specified. You can add additional parameters in the custom payload from your Dialogflow agent, which Twilio will include in the request to the action URL.

When a session is paused, the request from Twilio to your action URL has VirtualAgentStatus set to paused and VirtualAgentProviderData contains a PauseParameters property with any custom parameters provided in the custom payload.

For example, if your Dialogflow CX agent returns the following custom payload response to Twilio:

1
{
2
  "TWILIO_ACTION": "PAUSE",
3
  "memberId": "$session.params.member_id",
4
  "paymentAmount": "$122.34"
5
}

Twilio's request to your action URL will contain the following values in the PauseParameters field:

1
{
2
  "memberId": "abc123", 
3
  "paymentAmount": "$122.34"
4
}

To resume a session, send a request to Twilio with the TwiML <Connect><VirtualAgent> containing a nested <Config> noun. The <Config> noun can include the following settings:

• resumeEndUserId: This configuration setting is required. It represents the existing conversation participant that is resuming the session. Its value should be set to the EndUserId property from the VirtualAgentProviderData of the paused event.
• resumeEventName: This configuration setting is optional. Its value should be set to the name of a custom event to trigger in the Dialogflow CX bot when the session is resumed. A custom event allows you to prompt a specific response from the agent or progress the conversation with additional context that was collected during the pause period. A custom event handler can be defined and triggered when the session is resumed.

See the dynamic connector configuration section for more information on <Config>. Note that you can only resume a session on the same Call SID which initiated the conversation.

Below is an example of how to resume a session with both the resumeEndUserId and resumeEventName configuration settings:

1
<?xml version="1.0" encoding="UTF-8"?>
2
<Response>
3
	<Connect>
4
		<VirtualAgent connectorName="uniqueName">
5
			<Config name="resumeEndUserId" value="projects/ccai-test-customer/locations/us-east1/conversations/119qL_EbVa6QqascUqOqi0taw/participants/40aMiI3SQZaEbby-EIyhrw"/>
6
			<Config name="resumeEventName" value="customEventName"/>
7
		</VirtualAgent>
8
	</Connect>
9
</Response>

TwiML noun allows you to override your underlying Dialogflow CX Connector's configuration or pass additional parameters that change the behavior of your virtual agent. The <Config> noun is nested inside of <VirtualAgent>. <Config> has two attributes: name and value, both of which must be used every time you use <Config>.

For each configuration option you want to override, you must include a new <Config> noun. The name attribute then corresponds to one of your Dialogflow CX Connector's configuration options, such as language, sentimentAnalysis, voiceName, and welcomeIntent.

Additionally, there are attributes that are not present in your Dialogflow CX Connector configuration such as voiceModel, speechModel, speechModelVariant, but you can still set these attributes using <Config> noun nested inside of <VirtualAgent>.

Below are the configuration settings supported within <Config> TwiML noun:

For example, if you want to customize the TTS voice and language for the virtual agent interaction, you can supply the respective configuration settings inside the <Config/> attributes as follows:

1
const VoiceResponse = require('twilio').twiml.VoiceResponse;
2

3
const response = new VoiceResponse();
4
const connect = response.connect();
5
const virtualagent = connect.virtualAgent({connectorName: 'uniqueName'});
6
virtualagent.config({name: 'language', value: 'en-us'});
7
virtualagent.config({name: 'voiceName', value: 'en-US-Wavenet-C'});
8

9
console.log(response.toString());

1
<Response>
2
  <Connect>
3
    <VirtualAgent connectorName="uniqueName">
4
      <Config name="language" value="en-us"/>
5
      <Config name="voiceName" value="en-US-Wavenet-C"/>
6
    </VirtualAgent>
7
  </Connect>
8
</Response>