public function sendSms( $phoneNumber, $templateId, array $personalisation = array(), $reference = '', $smsSenderId = NULL ){

        return $this->httpPost(
            self::PATH_NOTIFICATION_SEND_SMS,
            $this->buildSmsPayload( 'sms', $phoneNumber, $templateId, $personalisation, $reference, $smsSenderId)
        );

    }