WhatsApp Takes advantage of a "store and ahead" system for exchanging messages among two users. Every time a consumer sends a message, it is stored with a WhatsApp server, which tries to ahead it to the addressee, and consistently requests acknowledgement of receipt. The request is then logged over the https://share.evernote.com/note/b6ac86c4-49b5-8a83-fcdd-e9f84e4317c6