Messages can be sent as part of Laravel's notifications system. A notifiable (such as a User model) should include the "twilio" channel in its via() method. When routing the notification, the phone number the message should be sent to should be returned.

namespace App\Models;

use Illuminate\Foundation\Auth\User as Authenticatable;
use Illuminate\Notifications\Notifiable;
use Illuminate\Notifications\Notification;

class User extends Authenticatable
{
    use Notifiable;

    /**
     * Get the notification's delivery channels.
     *
     * @param mixed $notifiable
     *
     * @return array
     */
    public function via($notifiable)
    {
        // This application's users can receive notifications by mail and Twilio SMS
        return ['mail', 'twilio'];
    }

    /**
     * Get the notification routing information for the Twilio driver.
     * 
     * @param Notification $notification
     * 
     * @return string
     */
    public function routeNotificationForTwilio($notification)
    {
        return $this->mobile_number;
    }
}

For notifications that support being sent as an SMS, you should define a toTwilio method on the notification class. This method will receive a $notifiable entity and should return a string containing the message text.

namespace App\Notifications;

use Illuminate\Notifications\Notification;

final class PasswordExpiredNotification extends Notification
{
    /**
     * Get the Twilio / SMS representation of the notification.
     *
     * @param mixed $notifiable
     * 
     * @return string
     */
    public function toTwilio($notifiable)
    {
        // The $notifiable in this example is your User model
        return sprintf('Hello %s, this is a note that the password for your %s account has expired.', $notifiable->name, config('app.name'));
    }
}

Your default connection is used for the notification channel by default. If your application utilizes multiple Twilio API connections, you can set the connection which should be used using the TWILIO_NOTIFICATION_CHANNEL_CONNECTION environment variable.