WhatsApp uses a "store and ahead" mechanism for exchanging messages amongst two buyers. Each time a person sends a concept, it is actually saved on a WhatsApp server, which tries to forward it towards the addressee, and continuously requests acknowledgement of receipt. CowperKettleCowperKettle 36.7k1818 gold badges138138 silver badges235235 bronze badges https://share.evernote.com/note/f5ed0f3d-3352-3d51-727d-10fa609eb157