# # NotificationChannel
Representing a notification channel for sending messages.
```php
use Xendit\Invoice\NotificationChannel;
```
## Enum
* `EMAIL` (value: `'email'`)
* `SMS` (value: `'sms'`)
* `WHATSAPP` (value: `'whatsapp'`)
* `VIBER` (value: `'viber'`)
* `XENDIT_ENUM_DEFAULT_FALLBACK` (value: `UNKNOWN_ENUM_VALUE`)
If you encounter `UNKNOWN_ENUM_VALUE`, it means that this ENUM is unavailable in your current SDK version. Please upgrade to get the newest ENUM.
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