No it isn't. RCS its a open cellular standard thats being deployed worldwide. Google does offer a backend for carriers to use (when you want to push your clou

No it isn't. RCS its a open cellular standard thats being deployed worldwide. Google does offer a backend for carriers to use (when you want to push your cloud offerings and have tons of engineers with nothing else to do just like AWS) but it's not required and carriers are rolling their own. The protocol itself is meant for inter-carrier communication and phones.