Not really sure why this was posted today. However, I see a lot of confusion / misinformation in the comments, so here is a simplified explanation of how RCS works, while recognizing the topic is more complex technically and commercially. (Source/disclaimer: I am a product manager at Twilio and work on RCS.)

Google bought Jibe Mobile in 2015. [1] The GSMA Universal Profile (UP) defines the industry standard for RCS features. [2] Messaging apps (for example, Google Messages or Messages on iOS) implement those features, and carriers expose them through a MaaP (Messaging as a Platform). The GSMA publishes UP updates periodically; UP v3 was released in February 2025 [3], though the latest publicly iOS version supports UP v2.4.

Most carriers globally now use Google’s Jibe MaaP instead of building their own as Google Messages supports the Jibe MaaP. That choice reduced the fragmentation that previously produced many inconsistent Android messaging experiences. In addition, I believe E2EE encryption was only added to the UP in v3, Google had previously added it to Google Messages outside of the spec, as as a result only worked when both users are using Google Messages.

iOS Messages can technically support any MaaP because the downloaded carrier profile specifies which MaaP URL to use.

A MaaP supports both person-to-person (P2P) and application-to-person (A2P) RCS. P2P RCS uses phone numbers. Carriers generally do not enable RCS on the business phone numbers companies use for SMS today. For A2P RCS, businesses must create a chatbot/agent entity in the MaaP with its own image, display name, and contact details. Google’s MaaP provides an interface for businesses to create those RCS agent profiles; carriers then approve which agents may message subscribers on their networks. Theoretically this also helps make it easier for messaging clients to reduce spam / fraud, since traffic from legitimate business will be more distinguishable from P2P fraudulent traffic—both from a technical perspective (phone number vs chatbot/agent entity) as well as from an end user experience (verified and branded display vs anonymous phone number).

If you're a business / brand, interested in getting started with RCS, check out this page with more info on how to get started with RCS: https://www.twilio.com/en-us/messaging/channels/rcs

1. https://techcrunch.com/2015/09/30/google-acquires-jibe-mobil... 2. https://www.gsma.com/solutions-and-impact/technologies/netwo... 3. https://www.gsma.com/solutions-and-impact/technologies/netwo...