The US carriers announced in 2019 their CCMI (Cross Carrier Messaging Initiative) to bring RCS. But that went nowhere and they killed it. That’s when they started using Google’s Jibe instead.

See: https://arstechnica.com/gadgets/2021/04/verizon-att-and-t-mobile-kill-their-cross-carrier-rcs-messaging-plans/. Interesting read in 2025. Since then a lot changed. Carriers switched to Jibe rather than rolling their own RCS, Apple started supporting RCS (China mandated they add support, but I’m surprised that they brought it to other countries too), and now RCS has an official end to end encryption protocol.

Can’t believe it’s been 6 years since that announcement.