Definition
RCS Business Messaging (RBM) is the business side of RCS. Verified brands send branded, interactive messages, such as rich cards, carousels and suggested replies, to users' native messaging app through an RBM agent and Google's RBM API.
In Google's model, a partner builds an RBM agent, which sends messages to a phone number through the RBM API as HTTP requests with JSON payloads. User replies and events arrive at the partner's webhook. If the device does not support RCS, the API returns a 404 error, and the business should fall back to another channel such as SMS.
According to Google's documentation, a message can include text (up to 3,072 characters), rich cards, carousels of 2 to 10 cards, media and PDFs (files up to 100 MiB), and up to 11 suggestions per message. Messages are encrypted in transit between agents, Google servers and devices, and Google scans them for malicious content.
Before an agent can reach real users, it must pass brand verification and launch approval by Google, the carriers, or both. Each agent declares a use case (OTP, transactional, promotional or multi-use) and a billing category (conversational or non-conversational).
RBM's main advantages over SMS are the verified sender, which helps against spoofing, and rich interactive content. Its main limitation is reach, which depends on carrier launches and device support in each country.