Glossary
RCS (Rich Communication Services)
The modern successor to SMS and MMS. RCS upgrades a phone’s default texting app with read receipts, typing indicators, high-resolution media, group chat and verified business messaging.
General definition
RCS, or Rich Communication Services, is a messaging standard designed to replace SMS and MMS as the default texting experience on mobile phones. It is defined by the GSMA’s Universal Profile and delivered through the phone’s native messaging app, so it needs no separate download. RCS runs over a data connection and falls back to SMS when data is unavailable.
Compared with plain text messaging, RCS adds a richer feature set:
- Read receipts and typing indicators
- High-resolution images, video and file sharing
- Group chat with named participants
- Reactions, replies and suggested actions
- Verified sender branding for businesses (RCS Business Messaging)
Google Messages drove RCS adoption on Android, and Apple added RCS support in iOS 18 in 2024, making richer messaging work across iPhone and Android for the first time.
RCS vs SMS, iMessage and in-app chat
RCS sits between two other worlds. Against SMS and MMS it wins on features and media quality. Against closed apps like iMessage or WhatsApp it is carrier-based and cross-platform, but it lives inside the phone’s texting app rather than inside your product.
For a business, that distinction matters. RCS is a channel for reaching consumers on their phone number. It is not a way to own the messaging experience inside your own app, website or portal, and it does not give you control over hosting, data residency or the underlying chat data, which regulated industries usually require.
RCS in the Ethora ecosystem
Ethora is not a carrier RCS provider. Ethora is for building your own branded, in-app messaging. The Chat SDK and AI SDK let you embed real-time chat, group rooms and AI agents directly inside your product across web, iOS and Android.
Teams often evaluate RCS and in-app chat for adjacent reasons: RCS to enrich the phone’s native texting, an SDK to own the conversation inside a product they control. When data ownership, self-hosting and compliance matter, for example in healthcare or finance, a self-hosted, HIPAA-ready chat platform gives guarantees that carrier RCS cannot.
