I know how imessage works but GreenMoneky said specifically that they all use SMS.
And again, it is apples fault that there is no imessage for android.
To an iPhone user, there is no difference. iMessage works for everything EXCEPT sharing rich text messaging, high res images and video
specifically with Android Users. And most iPhone users couldn't give a rats ass about that feature. So they use SMS/MMS because they can "talk" to everyone, even though they can only use advanced messaging app features with other iPhone users. The Tyranny of the Default.
This ONLY works in the US because we're the only large country where Apple has such a dominant marketshare. And in the case of teens, the iPhone has become so culturally ingrained in how kids grow up, that there is a real social stigma to being a "green bubble". That's why over 80% of US teens use an iPhone.
OF COURSE it is Apple's fault. And they will fight long and hard to ensure this remains the status quo for as long as possible.
Carriers adopting CCMI is at least a small, long-overdue step in the right direction. It is too bad Google couldn't strong-arm the carriers into leveling the playing field in the US messaging market. But everyone is too afraid of pissing off Apple here to really make any significant moves.