> This is a SMS client, not a chat client That is a subjective take that's mainly in your head. WhatsApp is a client for chatting, so it is a chat client. It

> This is a SMS client, not a chat client That is a subjective take that's mainly in your head. WhatsApp is a client for chatting, so it is a chat client. It does not use the SMS network, so it is not an SMS client. Some countries such as US and France had free SMS services, that enabled it to be used as chat. Other places SMS being costly it was used as a "write ideally one message" functionality, similar to email (which only costs in other ways, in human time, but not in actual bills). You can see this in the design of the Messages app in iPhone for example.