What happens when you switch to iMessage
When you turn on iMessage, your iPhone stops sending regular text messages (SMS) to other iPhone users and sends encrypted messages through Apple's servers instead. The change is automatic — you flip a setting, and from that moment on, messages to other iMessage users appear in blue bubbles instead of green ones. Messages to Android phones and non-iMessage devices stay green and still use SMS.
The main reason to make this switch is that iMessage encrypts your messages end-to-end, meaning Apple cannot read them even if it wanted to. SMS messages are not encrypted — your phone carrier can see them, and so can anyone who intercepts the signal. If you text mostly other iPhone users, iMessage also includes read receipts, typing indicators, and better photo quality than SMS allows.
One thing to know before you switch: if you later move to Android or stop using iMessage, you may miss text messages from iPhone users for a while. This happens because Apple's servers still think your phone number belongs to an iMessage account. We cover how to fix this in the section below.
Key Takeaways
- Turn on iMessage in Settings > Messages > iMessage on any iPhone, and it activates when ready for all your contacts who also use iMessage.
- Messages to iPhone users turn blue and encrypt automatically; messages to Android users stay green and use regular SMS.
- If you switch to Android later, deregister your phone number from iMessage on Apple's website or you may not receive texts from iPhone users.
- iMessage requires a Wi-Fi or cellular data connection, while SMS works without internet if your phone has a signal.
How to turn on iMessage on your iPhone
Open Settings on your iPhone and tap Messages. Look for the iMessage toggle at the top of the screen and turn it on. Your phone will connect to Apple's servers using your Apple ID, and within a few seconds the toggle will show a checkmark. That is all you need to do — iMessage is now active.
If the toggle does not appear or stays grayed out, make sure you are signed into an Apple ID in Settings > [Your Name] at the top of the Settings app. You also need an active internet connection (Wi-Fi or cellular data) for iMessage to work. If you have both of those and the toggle still will not turn on, try signing out of your Apple ID and signing back in.
Once iMessage is on, open the Messages app and start a conversation with another iPhone user. If it worked, the message bubble will be blue and you will see "Delivered" underneath instead of the usual SMS confirmation. If the bubble is still green, the other person either does not have iMessage turned on or their device does not support it.
Why some messages stay green even after you turn on iMessage
Green bubbles mean the message went through SMS, not iMessage. This happens for three reasons: the person you are texting does not have iMessage turned on, they are using an Android phone or older device that does not support iMessage, or there is a problem with your internet connection and your phone fell back to SMS as a backup.
You cannot force someone to use iMessage if they do not want to or cannot use it. If you text an Android user, your message will always be green and will always use SMS, even if you have iMessage turned on. This is normal and expected — iMessage only works between Apple devices.
If you see green bubbles when texting someone with an iPhone, ask them to check their own Settings > Messages > iMessage to make sure it is turned on. If it is already on, there may be a temporary connection problem. Try turning iMessage off and back on, or restart your phone.
What to do if you switch to Android or stop using iMessage
Before you move to Android, turn off iMessage on your iPhone. Go to Settings > Messages and toggle iMessage off. This tells Apple's servers that your phone number is no longer registered with iMessage.
If you already switched to Android without turning off iMessage first, you need to deregister your number on Apple's website. Go to iforgot.apple.com, sign in with your Apple ID, and look for the option to manage your devices or deregister your phone number. You can also text "STOP" to 2255 (Apple's short code) from your new Android phone, though this method is slower and less reliable.
The reason this matters is that when iPhone users text your old number, their phones still think it is an iMessage account. They send the message through iMessage instead of SMS, and it never reaches your Android phone. Deregistering removes your number from Apple's system so iPhone users' phones automatically switch back to SMS for your number.
iMessage versus SMS: when each one is useful
Use iMessage when you are texting other iPhone users and want encryption, read receipts, and better photo quality. iMessage requires an internet connection, so it works over Wi-Fi or cellular data but not in airplane mode or without any connection at all.
Use SMS when you are texting Android users, older phones, or people outside your country (international SMS rates may explore). SMS works without internet — it only needs a cellular signal. SMS is also the fallback if your iMessage connection drops, so your message still goes through.
If you text a mix of iPhone and Android users, you do not have to choose. iMessage handles iPhone users automatically, and SMS handles everyone else. Your Messages app treats them the same way, so you do not have to think about which protocol you are using.
Troubleshooting when iMessage will not turn on
If the iMessage toggle is missing or grayed out, first check that you are signed into an Apple ID. Go to Settings > [Your Name] and make sure you see your name and email at the top. If you are not signed in, tap "Sign in to your iPhone" and enter your Apple ID credentials.
Next, make sure you have an active internet connection. iMessage needs Wi-Fi or cellular data to set up and to send messages. Turn Wi-Fi off and on, or toggle airplane mode off and on, to reset your connection. Wait 10 seconds and try turning on iMessage again.
If iMessage still will not turn on, restart your iPhone completely. Hold the power button until you see the "slide to power off" screen, slide to turn it off, wait 10 seconds, then hold the power button again until you see the Apple logo. Once your phone restarts, go back to Settings > Messages and try turning on iMessage.
If none of these steps work, sign out of your Apple ID completely, restart your phone, and sign back in. Go to Settings > [Your Name] > Sign Out, confirm, restart, then sign back in with your Apple ID. This refreshes your connection to Apple's servers and often fixes set up problems.
How iMessage encryption works and what it protects
iMessage uses end-to-end encryption, which means only you and the person you are texting can read the message. Apple's servers pass the message along but cannot decrypt it, and neither can anyone else who intercepts it in transit. SMS messages are not encrypted at all — your carrier can read them, and so can anyone with access to the network.
This encryption protects the content of your messages but not the metadata — Apple still knows that you sent a message to a certain person at a certain time. If privacy is your main concern, iMessage is significantly more private than SMS, but it is not anonymous.
One thing to understand: iMessage encryption only works between two iMessage users. If you send an iMessage to someone and their phone is not connected to the internet, or if they do not have iMessage turned on, your phone automatically sends it as SMS instead, and it loses the encryption. You will see a notification that the message was sent as SMS in this case.
Frequently Asked Questions
Can I use iMessage without Wi-Fi?
Yes. iMessage works over Wi-Fi or cellular data. As long as your phone has an internet connection, iMessage will send. If you lose internet, your phone automatically falls back to SMS for that message, so it still goes through.
Will my iPhone contacts know I switched to iMessage?
No. iMessage turns on silently — your contacts will not get a notification. They will only notice when they see blue bubbles instead of green ones in your conversation thread, which happens automatically once iMessage is active on both phones.
What if someone texts me and I have iMessage turned off?
If they have iMessage on, their phone will try to send an iMessage first. When it fails, their phone automatically resends as SMS. You will receive the SMS version. There is a slight delay while this happens, but you will get the message either way.
Can I turn off iMessage for just one contact?
Not directly. iMessage is all-or-nothing in your settings. However, if you want to text one person via SMS only, you can start a new conversation with their phone number instead of their contact card, and some phones will send it as SMS. The easiest approach is to just let iMessage work normally — it handles both automatically.
Does iMessage work internationally?
Yes, iMessage works anywhere you have an internet connection, regardless of country. SMS may have international charges depending on your plan, but iMessage does not. This is one reason many people prefer iMessage for texting people abroad.