RCS vs SMS
SMS is the 30-year-old store-and-forward messaging service on SS7. RCS (Rich Communication Services) is the GSMA-defined IP-native successor, running over the IMS core with richer features and improving on end-to-end encryption.
| Attribute | RCS | SMS |
|---|---|---|
| Transport | IMS (SIP + MSRP) | SS7 MAP / Diameter S6c |
| E2E encryption | MLS-based E2EE (rolling out) | None |
| A2P sender ID | Verified business messaging | Trivially spoofed sender |
| Fraud model | Business-messaging pricing | A2P termination + grey routes |
| Attack focus | IMS / SBA surface | SS7 SRI-SM, SMS interception |
Verdict
RCS closes SMS's worst problems (spoofing, no encryption) but expands the IMS attack surface. Operators cannot decommission SMS in the medium term — enterprise A2P revenue and interop with non-RCS devices keep it live. Expect both to coexist through the 5G era.