I think no one outside US uses Messages, because in the US , SMS is free as it seems. Probably the rest of the world each single SMS costs money, so people use messenger apps to ensure that all their friends on BB, Android, iOS and whatever else can send and receive text for free and all features are compatible. This is a big reason why Whatsapp shot up in user base when there was a gap between BBM users and iphone/android users.
Messages I believe is free only iOS to iOS.
Messages I believe is free only iOS to iOS.