How to Switch a Text Message to iMessage on iPhone

iMessage is Apple's encrypted messaging service that works over Wi-Fi or data, not SMS

When you send a message on an iPhone, it automatically goes out as iMessage (shown in blue) if the recipient has an Apple device, or as a regular text message (shown in green) if they don't. You cannot manually change a message you've already sent from SMS to iMessage. However, you can control whether iMessage is turned on for future messages, resend a failed message as iMessage, or troubleshoot why a message sent as SMS when you expected it to go as iMessage.

The difference matters because iMessage uses your internet connection and includes read receipts and typing indicators, while SMS uses your cellular plan and works on any phone. If a message sent as green (SMS) and you want it to have gone as blue (iMessage) instead, the only option is to send it again after confirming iMessage is enabled.

Key Takeaways

Messages sent as SMS (green) cannot be converted to iMessage after they leave your phone, so you must resend them if you want iMessage features.
Turn on iMessage in Settings > Messages > iMessage to may support future messages to Apple device users send as blue messages.
A message sends as SMS instead of iMessage when iMessage is off, the recipient doesn't have an Apple device, or your internet connection failed.
You can long-press a sent message and choose "Resend as iMessage" if the option appears, which only works if the recipient's device now supports it.
Check that your Apple ID is signed in under Settings > Messages, because iMessage requires an active Apple account to function.

Turn on iMessage in your iPhone settings

Open the Settings app on your iPhone and tap Messages. Look for the toggle next to iMessage and make sure it is turned on (the switch will be green). If it is already on, iMessage is active and future messages to iPhone, iPad, and Mac users will send as blue messages automatically.

If the iMessage toggle is off or grayed out, tap it to turn it on. Your phone will connect to Apple's servers using your Apple ID. This process usually takes a few seconds. If the toggle stays grayed out, you may not be signed into an Apple ID on this device — go to Settings > [Your Name] and sign in with your Apple ID first.

Once iMessage is on, you do not need to do anything else. The iPhone automatically detects whether the person you are texting has an Apple device and sends the message as iMessage (blue) or SMS (green) accordingly.

Resend a message as iMessage if it went out as SMS

If a message already sent as green (SMS) and you want to send it as blue (iMessage) instead, open the conversation and long-press the message. A menu will appear with options. If Resend as iMessage appears, tap it. The message will send again, this time as iMessage, and the recipient will receive it twice — once as SMS and once as iMessage.

The "Resend as iMessage" option only appears if the recipient's device now supports iMessage. If they have an Android phone or older device, this option will not show up, because iMessage cannot be sent to non-Apple devices. In that case, the original SMS message is the only way to reach them.

If you do not see a resend option at all, try closing the Messages app completely and opening it again. Sometimes the menu takes a moment to load.

Check why a message sent as SMS instead of iMessage

A message sends as green (SMS) for three main reasons: iMessage is turned off on your phone, the recipient does not have an Apple device, or your internet connection failed at the moment you sent it.

First, confirm iMessage is on by going to Settings > Messages and checking that the iMessage toggle is green. Second, ask the recipient whether they have an iPhone, iPad, or Mac — if they use Android or another device, all messages will be SMS. Third, check your Wi-Fi or cellular data connection by opening a web browser and loading a website. If the page loads, your internet is working.

If iMessage is on and the recipient has an Apple device but messages still send as green, sign out of your Apple ID and sign back in. Go to Settings > [Your Name] > Sign Out, wait 30 seconds, then go back to Settings > [Your Name] and sign in again. This refreshes your iMessage registration and often fixes the problem.

Understand when iMessage fails and falls back to SMS

Sometimes iMessage attempts to send but fails, and your iPhone automatically sends the message as SMS instead. This happens when your internet connection drops during sending, when Apple's servers are temporarily unreachable, or when the recipient's device is not registered with iMessage at that moment.

When this happens, the message still reaches the recipient, but it goes as a green SMS rather than a blue iMessage. You will see a small "Not Delivered" label or an exclamation mark next to the message. Tap the message and choose Try Again to attempt sending as iMessage, or Send as Text Message to deliberately send it as SMS instead.

Make sure your Apple ID is signed in for iMessage

iMessage requires an active Apple ID on your device. If you recently changed your Apple ID password, signed out, or switched devices, iMessage may not work until you sign back in. Go to Settings > [Your Name] and confirm you are signed in. If you are not, tap Sign in to your iPhone and enter your Apple ID email and password.

If you are already signed in but iMessage is still not working, try signing out and signing back in. Go to Settings > [Your Name] > Sign Out, confirm you want to sign out, wait 30 seconds, then sign back in with your Apple ID. This process re-registers your phone with Apple's iMessage servers.

Frequently Asked Questions

Can I change a message from SMS to iMessage after I've already sent it?

No, once a message leaves your phone as SMS (green), it cannot be converted to iMessage. You must resend the message. Long-press the original message and tap "Resend as iMessage" if that option appears, which only works if the recipient has an Apple device.

Why do my messages to my friend's iPhone send as green instead of blue?

This usually means iMessage is off on your phone, your internet connection failed when you sent it, or your friend's device is not registered with iMessage at that moment. Check that iMessage is on in Settings > Messages, confirm your internet is working, and ask your friend to restart their iPhone.

Do I need to do anything special to send iMessage to someone?

No. Once iMessage is turned on in your settings, your iPhone automatically sends messages as iMessage to anyone with an Apple device and as SMS to anyone without one. You do not need to choose or configure anything per conversation.

What happens if I turn off iMessage?

All your messages will send as regular SMS text messages, even to people with iPhones. You will lose read receipts, typing indicators, and end-to-end encryption. Messages will still be delivered, but they will use your cellular plan instead of Wi-Fi or data.

If someone switches from iPhone to Android, will my old iMessages still show up?

Yes, all your old iMessage conversations stay in your Messages app. New messages to that person will automatically send as SMS (green) instead of iMessage (blue) because their new Android phone cannot receive iMessages.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.