I haven't heard much about this one and I can't figure out why not. Check out Telegram Messenger app. Lightning fast messages, read receipts, secure messaging... all great features. They're pledging to keep it completely free - no ads, no subscriptions... I hope this catches on and becomes the WhatsApp replacement. https://itunes.apple.com/us/app/telegram-messenger/id686449807 Nope, I'm not affiliated with them in any way - just a big fan from the first day I used it.