What is the relationship between Google and RCS Business Messaging, and how does the billing work?

The RCS service is coordinated by Google to allow businesses to send enriched messages (images, video, carousels, buttons, etc.) in the native messaging app on smartphones (iOS and Android). Operators are partners.

Operation

Creation of an RBM agent
Validation / Deployment by operators

Billing

Google offers 3 billing categories:

Category	Description	Billing
Basic	Simple text (≤ 160 characters)	Per message
Single	Rich message without response expected	Per rich message
Conversational	Interactive exchanges during 24 h	Per 24-hour window

Docs:

RBM Overview