RCS is an open source protocol that can be run by different 'operators'[0]. So it's not so much as an extension, as Google's implementation of the protocol (whi

RCS is an open source protocol that can be run by different 'operators'[0]. So it's not so much as an extension, as Google's implementation of the protocol (which is open source and can be added by other operators). [0]: https://en.wikipedia.org/wiki/Rich_Communication_Services https://en.wikipedia.org/wiki/Rich_Communication_Services