TwiML™ Voice: <Client>

The <Client> noun supports the following attributes that modify its behavior:

The url attribute allows you to specify a URL for a TwiML document that will run on the called party's end, after she answers, but before the parties are connected. You can use this TwiML to privately play or say information to the called party, or provide a chance to decline the phone call using <Gather> and <Hangup>. If answerOnBridge attribute is used on <Dial>, the current caller will continue to hear ringing while the TwiML document executes on the other end. TwiML documents executed in this manner are not allowed to contain the <Dial> verb.

The method attribute allows you to specify which HTTP method Twilio should use when requesting the URL in the url attribute. The default is POST.

When dialing out to a Client using <Dial>, an outbound call is initiated. The call transitions from the initiated state to the ringing state when the phone starts ringing. It transitions to the answered state when the call is picked up, and finally to the completed state when the call is over. With statusCallbackEvent, you can subscribe to receive webhooks for the different call progress events: initiated, ringing, answered, or completed for a given call.

The statusCallbackEvent attribute allows you to specify which events Twilio should call a webhook on. To specify multiple events separate them with a space: initiated ringing answered completed. If a statusCallback is provided and no status callback events are specified the completed event will be sent by default.

As opposed to creating an outbound call via the API, outbound calls created using <Dial> are initiated right away and never queued. The following shows a timeline of possible call events that can be returned and the different call statuses that a <Dial> leg may experience:

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The statusCallback attribute allows you to specify a URL for Twilio to send webhook requests to on each event specified in the statusCallbackEvent attribute. Non-relative URLs must contain a valid hostname (underscores are not permitted).

The statusCallbackMethod attribute allows you to specify which HTTP method Twilio should use when requesting the URL in the statusCallback attribute. The default is POST.

The parameters Twilio passes to your application in its asynchronous request to the StatusCallback URL include all parameters passed in a synchronous request to retrieve TwiML when Twilio receives a call to one of your Twilio numbers. The full list of parameters and descriptions of each are in the TwiML Voice Request documentation.

When the call progress events are fired, the Status Callback request also passes these additional parameters:

It is possible to include additional key value pairs that will be passed to the Voice SDK device instance (Web or Mobile). You can do this by using the nested <Parameter> TwiML noun.

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const VoiceResponse = require('twilio').twiml.VoiceResponse;
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const response = new VoiceResponse();
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const dial = response.dial();
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const client = dial.client();
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client.identity('user_jane');
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client.parameter({
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    name: 'FirstName',
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    value: 'Jane'
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});
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client.parameter({
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    name: 'LastName',
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    value: 'Doe'
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});
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console.log(response.toString());

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<?xml version="1.0" encoding="UTF-8"?>
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<Response>
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   <Dial>
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     <Client>
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        <Identity>user_jane</Identity>
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        <Parameter name="FirstName" value ="Jane"/>
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        <Parameter name="LastName" value ="Doe" />
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      </Client>
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    </Dial>
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</Response>

These custom parameters can retrieved using the SDKs. For the Voice JavaScript SDK, refer to Connection.customParameters, for iOS, refer to TVOConnectOption.params, and for Android, refer to ConnectOptions.getParams()

In this example, we want to connect the current call to a client named joey. To connect the call to joey, use a <Dial> verb with a <Client> noun nested inside.

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const VoiceResponse = require('twilio').twiml.VoiceResponse;
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const response = new VoiceResponse();
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const dial = response.dial();
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dial.client('joey');
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console.log(response.toString());

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<?xml version="1.0" encoding="UTF-8"?>
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<Response>
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    <Dial>
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        <Client>joey</Client>
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    </Dial>
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</Response>

You can use up to ten total <Number> and <Client> nouns within a <Dial> verb to dial multiple <Number>s and <Client>s at the same time. The first person to answer the call will be connected to the caller, while the rest of the call attempts are hung up.

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const VoiceResponse = require('twilio').twiml.VoiceResponse;
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const response = new VoiceResponse();
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const dial = response.dial({
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    callerId: '+1888XXXXXXX'
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});
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dial.number('858-987-6543');
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dial.client('joey');
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dial.client('charlie');
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console.log(response.toString());

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<?xml version="1.0" encoding="UTF-8"?>
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<Response>
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    <Dial callerId="+1888XXXXXXX">
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        <Number>858-987-6543</Number>
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        <Client>joey</Client>
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        <Client>charlie</Client>
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    </Dial>
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</Response>

In this case, we want to receive a webhook for each call-progress event when dialing a Voice SDK device using <Dial>.

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const VoiceResponse = require('twilio').twiml.VoiceResponse;
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const response = new VoiceResponse();
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const dial = response.dial();
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dial.client({
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    statusCallbackEvent: 'initiated ringing answered completed',
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    statusCallback: 'https://myapp.com/calls/events',
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    statusCallbackMethod: 'POST'
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}, 'joey');
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console.log(response.toString());

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<?xml version="1.0" encoding="UTF-8"?>
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<Response>
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    <Dial>
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        <Client
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         statusCallbackEvent='initiated ringing answered completed'
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         statusCallback='https://myapp.com/calls/events'
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         statusCallbackMethod='POST'>
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             joey
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        </Client>
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    </Dial>
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</Response>