What I find from many of my adult iPhone-using friends is that they've got Whatsapp installed and they'll reply to me if I message them there, but when they wan

What I find from many of my adult iPhone-using friends is that they've got Whatsapp installed and they'll reply to me if I message them there, but when they want to send me something out of the blue they forget about Whatsapp and it comes through over SMS because they're so used to sharing via 'Messages'. The exception would be the persistent group chats in WhatsApp, they seem to think of these like 'chat rooms' from back in the day. In fact, I would go further to say that WhatsApp is preferred in my age cohort for group messaging and organization purposes because it solves the "green bubble problem".