iMessage vs RCS vs SMS: Which Messaging Method Is Safest?

iMessage: Apple’s Encrypted Ecosystem

If you’re an iPhone user, chances are you’ve used iMessage—even if you didn’t realize it. iMessages are the blue bubble messages sent between Apple devices, and they are end-to-end encrypted by default. This means only the sender and the receiver can read the content, with Apple having no access to message data during transit or while stored on devices. In 2025, Apple took things a step further by introducing PQ3, a post-quantum encryption protocol designed to protect messages even against future quantum computing threats. With this implementation, Apple has made iMessage one of the most forward-looking secure communication platforms available to the public. However, iMessage’s encryption only works within the Apple ecosystem. If you send a message to someone using an Android device, the conversation defaults to SMS or RCS (depending on their device and network), and the encryption vanishes. This breakdown in security happens quietly, and many users don’t even realize their messages are suddenly exposed. That’s one of the primary limitations of iMessage: its encryption is fantastic—but only when you’re inside Apple’s walled garden. Additionally, while Apple doesn’t read your messages, they do back up your messages to iCloud unless you turn off iCloud Backup or use encrypted backups. If someone gains access to your iCloud account or Apple complies with a court order, your encrypted messages could still be exposed through the cloud.

SMS: The Least Secure Option

SMS, or Short Message Service, has been around since the early days of mobile phones. It’s the most widely used messaging protocol in the world—and also the least secure. Messages sent over SMS are not encrypted in any form. They travel in plain text over mobile networks, meaning that your wireless carrier, government entities, or hackers with access to the cellular infrastructure can easily intercept and read them. Worse, SMS messages are stored on the carrier’s servers and may be retained for weeks, months, or longer. This leaves them vulnerable to data breaches or legal access. SMS is also notoriously susceptible to SIM swapping and spoofing attacks, which can allow bad actors to hijack your phone number and intercept your two-factor authentication codes or impersonate you. Despite these security flaws, SMS remains the default fallback method for messages between iPhones and Androids, as well as many two-factor authentication systems. In 2025, cybersecurity experts strongly discourage using SMS for anything sensitive—especially when better, encrypted alternatives are readily available.

RCS: A Promising but Imperfect Upgrade

RCS, or Rich Communication Services, is Google’s modern replacement for SMS on Android devices. It adds features like read receipts, typing indicators, high-resolution media sharing, and—most importantly—encryption. As of 2023, Google enabled end-to-end encryption for one-on-one RCS chats using the Google Messages app, and in 2024, this encryption was expanded to group chats. However, there’s a catch: RCS encryption only works when both parties are using the Google Messages app and have RCS enabled. That means if you’re texting someone on a different app, a different phone brand, or through a carrier that doesn’t fully support RCS, the message may fall back to unencrypted SMS without warning. Additionally, Apple has long resisted implementing RCS on iPhones, though it recently announced limited support for RCS messaging in iOS 18—set to roll out later this year. That update will allow Android users to send RCS messages to iPhones, but those messages won’t receive full end-to-end encryption in the Apple ecosystem, at least initially. Another issue with RCS is fragmentation. Unlike iMessage or Signal, which work seamlessly across their respective platforms, RCS implementation varies by carrier, device manufacturer, and region. This inconsistency creates uncertainty for users who want to rely on secure communication.

Comparing the Three: Security Breakdown

Let’s compare the three methods based on key criteria:

• Encryption: iMessage offers consistent end-to-end encryption for Apple-to-Apple messaging. RCS offers encryption for Google Messages users but is inconsistent. SMS has no encryption at all.

• Cross-Platform Compatibility: SMS and RCS can work between Android and iPhone, but encryption breaks down. iMessage is limited to Apple users.

• Metadata and Cloud Storage: iMessage may back up messages to iCloud unless disabled. SMS and RCS messages may be stored on carrier servers, and RCS may retain metadata like timestamps and IP addresses. None of these platforms hide metadata as thoroughly as apps like Signal.

• Two-Factor Authentication (2FA): SMS is still widely used for 2FA, but it’s extremely insecure. iMessage and RCS are not used for 2FA systems, and security experts recommend using authentication apps or hardware keys instead.

• Resilience to Surveillance: iMessage offers the best resistance to surveillance among the three, though cloud backups remain a concern. RCS offers some protection depending on the implementation. SMS provides none.

What’s the Safest Way to Message in 2025?

If your communication needs to be truly secure, none of these three methods are your best bet. Apps like Signal, Threema, or Session offer stronger security by design, with end-to-end encryption that’s applied to all communications—regardless of platform. These apps also minimize metadata, offer disappearing messages, and avoid cloud backups unless explicitly enabled.  Still, when comparing just iMessage, RCS, and SMS, iMessage comes out ahead for Apple-to-Apple communications. It’s encrypted by default, now includes post-quantum protections, and has built-in safeguards like verification codes to check for impersonation. RCS is a vast improvement over SMS and is acceptable for many Android users communicating within the Google ecosystem, but its inconsistent encryption makes it less reliable. SMS should be used as a last resort for unimportant or low-risk communications.

In 2025, iMessage remains the safest of the three options—but only within the Apple ecosystem. RCS shows promise for Android users, especially with encryption in place, but it still suffers from limitations and inconsistent rollout. SMS is outdated, unencrypted, and unsafe for anything remotely sensitive. If you care about privacy, your safest path is to choose an app that prioritizes end-to-end encryption by default—regardless of what phone you or your contacts use. Until cross-platform encrypted messaging becomes the norm, staying secure means being selective not just about what you say, but how you say it.