RCS for Business, also called RCS Business Messaging (RBM), is Google's platform for branded RCS messages that land in the phone's default messaging app on Android and iOS, where carriers support RCS. Google's FAQ says businesses must go through a partner or messaging aggregator. Companies that want direct API access apply through a partner interest form, then build agents in the Developer Console.
Google publishes no price list. Its FAQ says costs vary by aggregator and carrier and are usually based on message volume, message type and location. Carriers invoice partners for traffic to their subscribers.
RCS for Business has no iMessage, and no SMS of its own: when a phone cannot receive RCS, the API returns an error and fallback is up to you or your partner. Messages come from a verified brand agent, not a phone number. Linq sends iMessage, RCS and SMS from real phone numbers with automatic fallback, at a flat monthly fee from $260 on Pro.
Brands and messaging providers that want verified, rich RCS messages and can work with carriers or a partner.