Apple Seeds iOS 26.4 Beta With Test Support for End-to-End Encrypted RCS Messaging

The iOS & iPadOS 26.4 developer beta 1 includes an initial implementation of end-to-end encryption (E2EE) for Rich Communication Services (RCS) messages as a test feature.
This builds on Apple’s prior work introducing RCS support in iOS (added with iOS 18) to provide richer messaging than traditional SMS/MMS (e.g., typing indicators, read receipts, multimedia).
RCS E2EE is not yet fully launched to customers in this beta; Apple explicitly notes it will be enabled in a future iOS 26 software update, and the feature currently remains “in beta.”

How the RCS Encryption Works in This Beta

A new toggle in Settings enables support for testing RCS E2EE messaging. This toggle is on by default in the beta.
However, availability is staged — not all beta testers will immediately be able to send/receive encrypted RCS messages, even if they see the toggle.

In this first beta, encryption is only operational between Apple devices (e.g., iPhone-to-iPhone) when RCS messaging is used instead of iMessage.
At present, cross-platform encrypted messaging with Android is not yet supported in this beta; Apple plans to roll that out later.
Apple’s release notes confirm the encrypted RCS implementation is incomplete and not ready to ship in the final iOS 26.4 release.

When an RCS message is encrypted under this test implementation, the Messages app will display a lock icon next to the message thread, similar to how iMessage indicates end-to-end encryption.
The lock icon also appears on traditional iMessage threads, which have supported E2EE since 2011.

RCS (Rich Communication Services) is an evolution of SMS/MMS standardized by the GSMA and designed to bring modern messaging features to native carriers and messaging apps.
In 2024–2025, the GSMA and major vendors (Apple, Google) agreed to incorporate end-to-end encryption into the RCS Universal Profile, enhancing privacy for cross-platform messaging.
The underlying encryption model is based on MLS (Message Layer Security), a modern messaging protocol supporting group chats and key exchange with forward secrecy and future post-quantum cryptography support (though specific implementation details in iOS aren’t yet public).

Carrier & Device Support: Apple notes that E2EE for RCS is not supported on all devices or carriers yet in this beta.
Staged Rollout: The feature’s availability will expand to more testers over time as Apple validates stability and interoperability.
Future Cross-Platform Goal: Full support for iPhone-to-Android encrypted RCS messaging is planned for later iOS 26 updates, but is not present in this developer beta.

Developers with access to iOS 26.4 beta 1 can explore RCS E2EE behavior and UI integrations by toggling the feature on and messaging between beta devices.
Because the implementation is experimental and subject to change, third-party apps or testing frameworks should not rely on this behavior for production communications yet.
The Messages app behavior (e.g., lock icons and thread state) offers early cues for E2EE status but may evolve in future builds.

Aspect	Status in iOS 26.4 Beta
RCS E2EE Support	Present for testing
Default Toggle	Enabled in Settings
Cross-Platform (Android) Support	Not yet supported
Carrier/Device Availability	Limited and staged
Public Release	Planned for future iOS 26 update
Encryption UI	Lock icon indicates encrypted threads