SMS vs MMS vs RCS vs iMessage: green and blue bubbles explained
Same messages app, four different ways your message can travel. Which one you get decides whether photos are sharp, whether you see typing dots, and whether it works without data.
Side by side
| SMS | MMS | RCS | iMessage | |
|---|---|---|---|---|
| Travels over | Mobile network signalling | Mobile data | Mobile data or Wi-Fi | Mobile data or Wi-Fi |
| Works with no data | Yes | No | No (falls back to SMS) | No (iPhone can fall back to SMS) |
| Length | 160 plain or 70 Unicode characters per part | Long text plus media | Long text | Long text |
| Photos | No | Yes, heavily compressed (often a few hundred KB) | Yes, much higher quality | Yes, full quality |
| Typing dots and read receipts | No | No | Yes | Yes |
| Who it reaches | Any phone | Almost any phone with data | Phones with RCS turned on | Apple devices only |
| Costs | Your text allowance | Allowance or data, depends on plan | Data or Wi-Fi | Data or Wi-Fi |
Why texts fall back to green
Your phone picks the best route the other person can receive. If they don't have iMessage or RCS turned on, or either of you has no data right now, it falls back to SMS or MMS. Turning off mobile data, running out of data, or the other person switching phones can all turn a chat green. On iPhone, RCS lives under Settings, Apps, Messages, RCS Messaging. On Android, Google Messages calls it RCS chats (older versions say Chat features).
Why photos in texts look blurry
MMS has a small size limit set by the network, often around 300 KB to 1 MB, so the phone shrinks the picture a lot before sending. RCS and iMessage send far bigger files. If you're stuck on MMS, share a link instead, or shrink the photo yourself so you choose the quality: the image compressor does it in your browser.
Is it private?
SMS and MMS are not end-to-end encrypted: the network can read them, and texts can be redirected by SIM-swap fraud, which is why codes sent by text are the weakest kind of two-step login. iMessage is end-to-end encrypted. RCS in Google Messages is end-to-end encrypted between Google Messages users; encryption between iPhone and Android over RCS depends on both phones' software, so check for the lock icon rather than assuming.
Related
Not getting texts after switching phones · Text says Sent but not Delivered · Why a text gets split into several · interactive Wirebook lesson on how a text finds a phone
Questions
Why are some of my iPhone messages green?
Green means the message went as SMS, MMS or RCS instead of iMessage, usually because the other person doesn't have iMessage (they use Android) or one of you had no data at that moment.
Does RCS use data?
Yes. RCS goes over mobile data or Wi-Fi, like a chat app. If neither is available it falls back to SMS.
Is RCS better than SMS?
For most things, yes: typing dots, read receipts, full-quality photos, group chats and Wi-Fi support. SMS is still the fallback that works with no data.
Why are pictures sent by text blurry?
They went by MMS, which has a small size limit set by the network, so the phone shrinks them a lot. RCS and iMessage send much bigger files.
Are SMS texts encrypted?
Only between your phone and the mast. The network can read them, so they're not end-to-end encrypted. Prefer an app or RCS chat with a lock icon for anything private.
Published 路 updated .