# TwiML™ Voice: \ The [``](/docs/voice/twiml/dial) verb's `` noun lets you set up VoIP sessions to clients using the [WhatsApp](https://www.whatsapp.com/) consumer application. With this feature, you can send a call to any WhatsApp endpoint, after first establishing consent using a [WhatsApp message template](/docs/whatsapp/key-concepts#message-templates). Set up your TwiML to use the `` noun within the `` verb to connect a Voice call to a WhatsApp client. If you are unfamiliar with WhatsApp Business Calling, or want more information on how Twilio works with WhatsApp, see the Twilio [WhatsApp Business Platform](/docs/whatsapp) documentation. ## Basic usage The TwiML example below shows the basic TwiML syntax of ``. ```html +555551234567 ``` > \[!NOTE] > > All WhatsApp calls must use a `callerId` set to a registered, Voice-activated WhatsApp sender in the format `whatsapp:{sender}` on the originating Twilio account. *** ## `` attributes The `` noun supports the following attributes that modify its behavior: | Attribute name | Allowed values | Default value | | :--------------------------------------------------------- | :---------------------------------------------- | :------------ | | [`url`](#attributes-url) | Any URL | none | | [`method`](#attributes-method) | `GET`, `POST` | `POST` | | [`statusCallbackEvent`](#attributes-statuscallbackevent) | `initiated`, `ringing`, `answered`, `completed` | none | | [`statusCallback`](#attributes-statuscallback) | Any URL | none | | [`statusCallbackMethod`](#attributes-statuscallbackmethod) | `GET`, `POST` | `POST` | WhatsApp destination numbers specified in the noun should be formatted in [E.164 format](/docs/glossary/what-e164) with a `+` and country code, for example: `+16175551212`. ### `url` attribute \[#attributes-url] The `url` attribute allows you to specify a URL that will return a TwiML response to be run on the called party's end, after they answer, but before the parties are connected. You can use this TwiML to privately `` or `` information to the called party. You could also provide a chance to decline the phone call using `` and ``. The `url` attribute doesn't support any other TwiML verbs. If the [`answerOnBridge`](/docs/voice/twiml/dial#answeronbridge) attribute is used on ``, 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 `` verb. ### `method` attribute \[#attributes-method] 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`. ### `statusCallbackEvent` attribute \[#attributes-statuscallbackevent] When dialing out to a number using ``, 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 for a given call: `initiated`, `ringing`, `answered`, or `completed`. Non-relative URLs must contain a valid hostname. Underscores aren't permitted. The `statusCallbackEvent` attribute allows you to specify which events Twilio should trigger a webhook on. To specify multiple events, separate them with a space: `initiated ringing answered completed`. If a `statusCallback` is provided and no `statusCallbackEvent` 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 `` 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 `` leg may experience: ![Timeline of an outbound Dial call showing events: initiated, ringing, answered, completed.](https://docs-resources.prod.twilio.com/8fbb66cf4210d21b105f64f4ba77ab24a09cec1acdd4e6e56f889e3ecf9e2388.png) | Event | Description | | :---------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | `initiated` | The `initiated` event is fired when Twilio starts dialing the call. | | `ringing` | The `ringing` event is fired when the call starts ringing. | | `answered` | The `answered` event is fired when the call is answered. | | `completed` | The `completed` event is fired when the call is completed, regardless of the termination status: `busy`, `canceled`, `completed`, `failed`, or `no-answer`. If no `statusCallbackEvent` is specified, `completed` will be fired by default. | ### `statusCallback` attribute \[#attributes-statuscallback] The `statusCallback` attribute allows you to specify a URL for Twilio to send webhook requests to on each event specified in the `statusCallbackEvent` attribute. ### `statusCallbackMethod` attribute \[#attributes-statuscallbackmethod] 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`. ### Status callback HTTP parameters 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](/docs/voice/twiml#twilios-request-to-your-application) documentation. When the call progress events are fired, the `statusCallback` request also passes these additional parameters: | Parameter | Description | | :------------------ | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `CallSid` | Unique identifier for this call that Twilio generates. To modify the child call, make a `POST` request to `Calls/{CallSid}` with a new TwiML URL. | | `ParentCallSid` | A unique identifier for the parent call. | | `CallStatus` | A descriptive status for the call. The value is one of `queued`, `initiated`, `ringing`, `in-progress`, `busy`, `failed`, or `no-answer`. See the [CallStatus section](/docs/voice/api/call-resource#call-status-values) for more details. | | `CallDuration` | The duration in seconds of the just-completed call. Only present in the `completed` event. | | `RecordingUrl` | The URL of the phone call's recorded audio. This parameter is included only if `record` is set on the `` and does not include recordings initiated in other ways. `RecordingUrl` is only present in the `completed` event. | | `RecordingSid` | The unique ID of the [Recording](/docs/voice/api/recording) from this call. `RecordingSid` is only present in the `completed` event. | | `RecordingDuration` | The duration of the recorded audio (in seconds). `RecordingDuration` is only present in the `completed` event. To get a final accurate recording duration after any trimming of silence, use [`recordingStatusCallback`](/docs/usage/webhooks/voice-webhooks#recording-status-callbacks). | | `Timestamp` | The timestamp when the event was fired, given as UTC in [RFC 2822](https://datatracker.ietf.org/doc/html/rfc2822) format. | | `CallbackSource` | A string that describes the source of the webhook. This is provided to help disambiguate why the webhook was made. On Status Callbacks, this value is always `call-progress-events`. | | `SequenceNumber` | The order in which the events were fired, starting from 0. Although events are fired in order, they are made as separate HTTP requests, and there is no guarantee they will arrive in the same order. |