The Viber channel object for [Advanced promotional](https://www.bulkgate.com/en/docs/advanced-api/advanced-promotional/2.0/). It goes into the `channel` object under the `viber` key - see [Cascade](https://www.bulkgate.com/en/docs/advanced-api/advanced-cascade/).

> [!IMPORTANT]
> Transactional messages use a **different** Viber object under the same key - it carries approved templates instead of a button and an image. See [Viber – transactional](https://www.bulkgate.com/en/docs/advanced-api/advanced-viber-transactional/).

```json
{
	"viber": {
		"sender": "BulkGate",
		"image": "https://example.com/banner.jpg",
		"button": {
			"caption": "Open the offer",
			"url": "https://example.com/offer"
		}
	}
}
```

## Viber object

| PARAMETER NAME | VALUE                                                                                                                                        | MANDATORY | DEFAULT VALUE |
|:---------------|:-----------------------------------------------------------------------------------------------------------------------------------------------|:---------:|:-------------:|
| text           | Text of the Viber message. Overrides the top-level `text`, see [Which text is used](https://www.bulkgate.com/en/docs/advanced-api/advanced-cascade/)                                |    No     |    `null`     |
| sender         | Registered Viber sender. Needs to be registered first. For registration contact support [here](https://www.bulkgate.com/en/contact-us/)                         |  **Yes**  |       -       |
| expiration     | Time limit in seconds after which the next channel in the cascade is used. Values below `60` are ignored and replaced by the default          |    No     |     `300`     |
| button         | Structure that creates a button in the message, see [Button object](#button-object). Without it the message has no button                     |    No     |    `null`     |
| image          | Url to an image shown in the message                                                                                                         |    No     |    `null`     |

### Button object

| PARAMETER NAME | VALUE       | MANDATORY | DEFAULT VALUE |
|:---------------|:------------|:---------:|:-------------:|
| caption        | Button text |    No     |     `OK`      |
| url            | URL address |    No     |      `#`      |

The defaults apply only when the `button` object itself is present - `"button": {}` produces a button captioned `OK` pointing to `#`.

## Example of full request

Viber with an image and a button, SMS as the fallback. The SMS leg has no image or button, so it falls back to the top-level `text`.

```http-json
POST /api/2.0/advanced/promotional HTTP/1.1
Host: portal.bulkgate.com
Content-Type: application/json

{
	"application_id": 451,
	"application_token": "NKN02TWE6NfBkfl-your-secret-token-Wf05GaqLIWLW4aBj",
	"number": ["420777777777", "420777777778"],
	"text": "Spring sale starts today, up to 50 % off.",
	"channel": {
		"viber": {
			"sender": "BulkGate",
			"image": "https://example.com/spring-sale.jpg",
			"button": {
				"caption": "Open the offer",
				"url": "https://example.com/spring-sale"
			}
		},
		"sms": {
			"sender_id": "gText",
			"sender_id_value": "BulkGate"
		}
	}
}
```

The response is the same for every channel - see [Advanced promotional](https://www.bulkgate.com/en/docs/advanced-api/advanced-promotional/2.0/).