For more than a decade, communicating between iPhone and Android handsets over mobile networks felt like stepping into a time capsule. While chats between two iPhones benefited from modern iMessage capabilities, texting an Android contact defaulted to legacy SMS and MMS standards introduced in the 1990s—resulting in pixelated compressed videos, broken group chats, and missing delivery confirmations. With the release of iOS 18, Apple officially adopted the GSMA Rich Communication Services (RCS) Universal Profile standard.
RCS modernises cross-platform messaging between Apple and Android devices, bringing high-resolution media sharing, live typing indicators, delivery and read receipts, and stable group chats to your green-bubble conversations. Here is an authoritative guide on how RCS works on iOS 18, its carrier prerequisites, and how to verify it is active on your iPhone.
What Changes with RCS on iPhone?
When chatting with an Android user using RCS, the conversation still displays green bubbles to indicate non-iMessage transport, but gains significant capability upgrades:
- Full-Resolution Photos and 4K Video: Bypasses extreme MMS carrier compression limits (typically 1 MB), allowing crisp photos and videos to transfer smoothly.
- Live Typing Indicators: Displays active animated bubbles when the other participant is typing a response.
- Delivery and Read Receipts: Confirms when your message was successfully delivered to the recipient’s phone and when it was opened.
- Wi-Fi and Cellular Data Messaging: Routes text and media over active Wi-Fi networks when cellular reception is weak or unavailable.
- Enhanced Group Chats: Add, remove, or rename participants in cross-platform groups without breaking message delivery.
Prerequisites for RCS on iPhone
To use RCS messaging, verify that your device satisfies the necessary conditions:
- iOS Version: iPhone running iOS 18 or higher.
- Carrier Support: Your mobile cellular carrier must support the RCS Universal Profile for Apple devices (major carriers across the UK, Europe, and US have active support).
- Recipient Device: The Android contact must have RCS / Chat Features enabled in Google Messages or their carrier messaging app.
How to Enable and Verify RCS on iPhone
RCS is enabled by default upon updating to iOS 18 on supported networks. You can confirm or toggle the setting manually:
- Open the Settings app on your iPhone.
- Scroll down and tap Apps, then select Messages (or tap Messages directly on the main Settings screen).
- Under the Text Messaging section, locate RCS Messaging.
- Ensure the toggle switch next to RCS Messaging is turned On.
- If the toggle switch does not appear, your carrier has not yet deployed carrier bundle support for RCS on iOS 18; verify with your carrier for regional rollout schedules.
How to Tell If You Are Using RCS in a Conversation
When opening a conversation with an Android contact in the Messages app:
- Look at the text composition input field before typing.
- If RCS is active, the placeholder watermark reads Text Message • RCS.
- If the connection falls back to legacy carrier protocols due to poor coverage or lack of recipient support, the watermark reads Text Message • SMS.
| Feature | Legacy SMS / MMS | RCS Messaging (iOS 18) | iMessage (Apple-to-Apple) |
|---|---|---|---|
| Media Quality | Heavily compressed (low res) | High resolution (Photos & Video) | Lossless full resolution |
| Typing Indicators | No | Yes (Live bubbles) | Yes |
| Transmission Path | Cellular voice/signaling bands | Cellular data & Wi-Fi | Apple Push Notification Service |
| Bubble Colour | Green | Green | Blue |
Managing Read Receipts in RCS
If you prefer not to broadcast when you have read incoming messages from Android contacts, you can toggle read receipts independently in Settings > Apps > Messages > Send Read Receipts.