Whatsapp is a social media platform connecting people through Telkom and other service providers. As an application, WhatsApp costs nothing although most service providers need your data subscription for you to access it. Telkom suggests that subscribing to their FreeMe bundle means that using Whatsapp won’t eat into any of your data.
However, you need to ensure that your FreeMe bundle is active with a data subscription on it to enable you to use WhatsApp without using up your data. Once FreeMe has run out, the messaging service will then start costing you.