Apple on Monday released the second developer beta of iOS 27, build 24A5370h, marking the first significant update since the operating system debuted at WWDC 2026 two weeks ago. The beta ships two features with wide reach: Write with Siri, an on-device AI writing assistant that replaces the previous Writing Tools feature entirely, and inline replies for RCS conversations with Android users — a threading capability the GSMA's Universal Profile specification has defined since June 2024.

Both features are available to registered developers now. A public beta is expected in July, with iOS 27 scheduled for general release alongside the iPhone 18 in September.

Write with Siri Replaces Writing Tools in Every App

iOS 27 Beta 2 introduces Write with Siri as the system-wide replacement for Writing Tools, the AI-powered text-editing panel Apple shipped with iOS 18.1. The older interface — which offered preset tones such as "Friendly" and "Professional" in a floating menu — is gone. In its place, a prominent "Write with Siri" prompt now appears in the keyboard suggestions bar whenever a user is editing text in Notes, Mail, Messages, or any app using Apple's standard system text components. Tapping it opens a natural-language input field that slides down from the Dynamic Island, where users can describe in plain language what they want: generate text from scratch, proofread a draft, or rewrite content in a different register.

Early developer reports describe the transition as substantive rather than cosmetic. The old preset buttons enforced a fixed vocabulary for changes; Write with Siri accepts open-ended instructions and acts on them using on-device inference, meaning the text never leaves the device during the base operation. The previous Writing Tools feature required text to be selected before the panel appeared; in Beta 2, the Write with Siri button surfaces before the user types a single character, lowering the activation threshold.

How Write with Siri Runs Without Sending Your Text to the Cloud

Write with Siri's most distinctive engineering claim is that its base inference is local. Apple's on-device language model for Apple Intelligence is approximately 3 billion parameters, optimized for Apple silicon through 2-bit quantization-aware training and a technique called KV-cache sharing, which reduces memory bandwidth requirements when the model processes long contexts. These architectural choices let a model that would otherwise require substantially more memory run on the Neural Engine built into A-series and M-series chips without routing a user's draft text to a remote API.

The design reflects a deliberate engineering tradeoff: the on-device model is smaller than the server-side model Apple uses for more complex Apple Intelligence tasks — the server model uses a Parallel-Track Mixture-of-Experts architecture on Private Cloud Compute — so Write with Siri is faster and private for everyday writing, while more demanding requests can escalate to the server model if needed. Users who want to audit which requests leave their device can check Settings > Privacy & Security > Apple Intelligence Report, where Apple logs cloud versus on-device processing.

One meaningful constraint: Write with Siri, like the rest of Siri AI, is not available to iPhone or iPad users in the European Union when iOS 27 ships this fall. Apple confirmed that Siri AI will be absent from iOS and iPadOS in the EU because the company and EU regulators have not reached agreement on how to implement the features without what Apple characterized as requirements for "nearly unlimited device access" under their interpretation of the Digital Markets Act. Mac and Apple Vision Pro users in the EU can access Siri AI when set to a supported language. Siri AI features are also unavailable in China pending regulatory approval. Craig Federighi, Apple's senior vice president of Software Engineering, stated the company has no current timeline for EU availability on iOS or iPadOS.

RCS Inline Replies: Two Years After the Spec, Apple Delivers

The second major addition in Beta 2 is inline threading for RCS conversations. iPhone users can now long-press a message in an RCS chat with an Android contact, select a reply option, and send an inline reply that quotes the specific message — the same interaction pattern that has long existed inside iMessage blue-bubble conversations.

The timing deserves context. The GSMA published Universal Profile 2.7 in June 2024, and inline threading was among its headline additions alongside custom emoji reactions, message editing, and message recall. Apple launched iOS 18 with RCS support in September 2024, but implemented only Universal Profile 2.4, a specification from October 2019. That gap — shipping RCS in September 2024 while omitting features from a June 2024 specification — is what iOS 27 begins to address.

As 9to5Google noted Monday, the GSMA has since published Universal Profile 3.0 and 4.0, meaning Apple's iOS 27 implementation will bring iPhones to UP 2.7 compliance while the standards body is two versions further ahead. Writer Jesse Hollington at iDrop News described Apple as "still dragging its heels" on the standard while crediting the feature as a meaningful improvement for cross-platform group chats.

Beta 2 also corrects a reaction display problem: when an iPhone user reacted to an image in an RCS chat, Android recipients previously received a separate text message — "Aaron loved an image" — instead of the emoji appearing on the image itself. iOS 27 fixes this so emoji reactions render on images and videos in RCS, matching iMessage behavior. Macworld noted that the inline reply feature is functional in Beta 2 but "quite buggy" and does not always behave as expected at this early stage.

For RCS threading to work, both the iPhone and the Android device — and their respective carriers — must support RCS. Most major US carriers, including AT&T, T-Mobile, and Verizon, use Google's Jibe platform for RCS and support the feature on Android.

What Else Ships in Beta 2

Beyond the two headline features, Beta 2 adds the ability to update an Apple TV directly from the Home app on iPhone — previously requiring the Apple TV to be powered on first — and previews a new Wallet Insights section where users will be able to connect financial accounts to see spending data, though the feature remains incomplete. The Siri voice customization settings for Pace and Expressivity, targeted at iPhone 17 Pro and iPhone Air users, are now labeled "Coming Soon" rather than active, indicating those capabilities are not yet ready for testing. AI editing tools in Photos have gained support for RAW images in this beta. HomeKit bug fixes resolve an incompatibility with Philips Hue lights that affected Beta 1. A full breakdown of all Beta 2 changes is available from MacRumors.

How to Install iOS 27 Beta 2

Registered developers can download build 24A5370h through Settings > General > Software Update, with Beta Updates set to iOS 27 Developer Beta. The matching betas for iPadOS 27, macOS Golden Gate (macOS 27), tvOS 27, and visionOS 27 were released simultaneously on June 22.

Apple advises against installing beta software on a primary device. Users should expect bugs, battery life degradation, and app compatibility issues during the developer beta phase. The first public beta, intended for early adopters without a developer account, is expected to arrive in July via beta.apple.com.

Frequently Asked Questions

What is Write with Siri in iOS 27?

Write with Siri is Apple's new system-wide AI writing assistant, introduced in iOS 27 Beta 2, that replaces the previous Writing Tools feature. It appears as a prompt in the keyboard suggestions bar in apps including Notes, Mail, and Messages. Users describe what they want in natural language — generating, proofreading, or rewriting text — and Siri processes the request using Apple's on-device language model, which runs locally on the device without sending drafts to a cloud server for most operations.

Does iOS 27 fix RCS messaging between iPhone and Android?

iOS 27 Beta 2 adds inline replies and proper emoji reactions to RCS conversations, two features that have been part of the GSMA's Universal Profile 2.7 specification since June 2024. With this update, iPhone users can long-press a message in a green-bubble RCS chat and reply directly to it, matching the threading behavior that iMessage provides. The feature is functional but reported as buggy in the current beta. Both sender and recipient must be on devices and carriers that support RCS for threading to work.

When does iOS 27 come out for everyone?

Apple plans to release the first iOS 27 public beta in July 2026 for users who register at beta.apple.com. The final public release of iOS 27 is expected in September 2026, coinciding with the launch of the iPhone 18 lineup. iOS 27 supports iPhone 11 and newer, though Write with Siri and other Siri AI features require Apple Intelligence-capable hardware and are not available in the EU or China at launch.

Which iPhones support Write with Siri and Siri AI?

iOS 27 itself installs on iPhone 11 and newer models, including iPhone SE 2 and later. Siri AI features, including Write with Siri, require Apple Intelligence-compatible hardware — generally iPhone 16 or later. The most powerful on-device AI model, enabling features such as expressive voice customization, requires iPhone 17 Pro or iPhone Air. Siri AI, including Write with Siri, will not be available in the EU or China when iOS 27 launches.