Here's how green bubbles are getting upgraded in iOS
Briefly

With the rollout of iOS 18, Apple has integrated Rich Communication Services (RCS) support into iPhones, significantly enhancing messaging between iOS and Android devices.
RCS on iOS brings essential features like high-resolution media, typing indicators, and read receipts, improving the experience for chats between iPhone and Android users.
While RCS offers many improvements over SMS and MMS, it still lacks some iMessage specialties such as scheduled messages and animated text effects.
To identify if a conversation is via RCS, look for the text-entry box, where it indicates 'Text Message' followed by either 'RCS' or 'SMS'.
Read at The Verge
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