Read receipts not working on my iPhone

Read Receipts: When They Work and When They Ghost You

Read Receipts are a nifty feature that lets you know when someone has seen your message—but their behavior depends heavily on the type of message you're sending.

• iMessage: If you're messaging another Apple user through iMessage (those lovely blue bubbles), read receipts work perfectly if both parties have the feature enabled in Settings. When turned on, you'll see a "Read" timestamp under your sent message when the recipient opens it. Apple handles this entirely over the internet via iCloud, so it's not reliant on your mobile carrier.
• SMS/MMS (Green Bubbles): Here's where things get murky. Standard SMS and MMS messages—those green bubble texts—are old-school tech that runs through your cellular carrier, not Apple. Most carriers don’t support read receipts for SMS/MMS. A few may offer something similar as part of RCS (Rich Communication Services), but iPhones don’t currently support RCS (as of iOS 18.3), so you're out of luck. In short: no blue bubble = no read receipts.

So, if you're wondering why you never see "Read" under a message to your Android-using friend or on a group chat with mixed devices—it's not ghosting, it's just the tech.