I'm having an issue with the new messaging   update. Some of my conversations with individuals are stuck as your new "chat" feature instead of SMS and make it so I have to be connected to wifi or us data to send a message. They also have to be using the same app to receive my messages.  How do I change this? I've tried deleting the conversation but that doesn't fix it.  This only affects certain contacts.  Thier names appear in blue when I try starting a new conversation.  Is there a way to disable the "chat" feature?