RCS is a modern, internet-based messaging protocol that allows Android and iPhone users to send high-resolution photos and videos, see typing indicators, and receive read receipts, features all typically present in instant messaging apps. It is built on an industry specification called the RCS Universal Profile.

“When RCS messages are end-to-end encrypted, they can’t be read while they’re sent between devices,” Apple said in a statement. “Users will know that a conversation is end-to-end encrypted when they see a new lock icon in their RCS chats.”

Apple began testing with E2EE in RCS messages in iOS and iPadOS 26.4 Beta, initially limiting it to only conversations between Apple devices. In early 2025, the GSM Association (GSMA) announced support for E2EE for safeguarding messages sent via the RCS protocol.