iMessage Not Working or Not Delivered on iPhone: Fixes in Order

If iMessage is not working on your iPhone, check that iMessage is switched on under Settings, Apps, Messages, confirm your connection, and check which number or email address Messages uses under Send & Receive. For a message marked Not Delivered, tap the red exclamation point, tap Try Again, and then choose Send as Text Message if it still fails.

This guide follows Apple's support articles, checked on 2026-10-31, in the order you should try them. It also explains why bubbles turn green, because a green bubble is often normal behavior and not a fault.

Who this is for and what you will have at the end

This is for iPhone users whose messages show as green when they expect blue, will not send, show a red exclamation point and Not Delivered, stop arriving on one device, or will not activate after setup. At the end you will know which of these you have, which setting to change, and when the cause is the other person's phone or your carrier.

Menu names below are the ones in Apple's current pages. On older versions of iOS the Messages settings may sit in a slightly different place.

First: what blue and green bubbles mean

Apple's support pages explain the difference:

Apple says a message is green when it is sent as RCS or MMS/SMS instead of iMessage, for one of these reasons:

• The recipient does not have an Apple device.
• iMessage is turned off on your device or the recipient's.
• iMessage is temporarily unavailable on either device.
• You need to update Messages settings after setting up a new device.

So a green bubble to an Android phone is expected. A green bubble to someone you know has an iPhone is the case worth troubleshooting.

Step 1: Check the basics

1. Update iOS. Apple's first suggestion after setup problems is to update to the latest iOS if needed.
2. Check your connection. iMessage, RCS and MMS need cellular data or Wi-Fi. SMS needs a cellular connection, unless you turn on Wi-Fi Calling, which lets SMS work over Wi-Fi.
3. Check your phone line. Go to Settings > Cellular and make sure your phone line is turned on. If you use more than one SIM, select and turn on the number you want to use.
4. Restart the iPhone. Apple lists a restart among its general steps.
5. Check the contact. Confirm that you entered the correct phone number or email address for the person.

Step 2: Turn iMessage on and choose your number

1. Open Settings and tap Apps.
2. Tap Messages.
3. Turn iMessage off, then turn it back on.
4. Tap Send & Receive.
5. Tap the phone number you want to use with Messages.

This is Apple's procedure for problems after setting up a new device. It also fixes many cases where iMessage was never turned on, which makes everything green.

Send as Text Message

To send automatically as a text when iMessage is not available, go to Settings > Apps > Messages and turn on Send as Text Message. Apple's page says this sends the message as an SMS when iMessage is not available. Text messages need a messaging plan, and rates may apply.

Step 3: Fix Not Delivered

A red exclamation point and "Not Delivered" mean the message did not go. Apple's steps are:

1. Check your network connection.
2. Tap the red exclamation point, then tap Try Again.
3. If the message still will not send, tap the red exclamation point and choose Send as Text Message. Apple notes that messaging rates may apply.

If you still get a Not Delivered alert after sending as text, the cause is usually the carrier or the recipient's number. Contact your carrier and confirm that it supports SMS, MMS or RCS on your plan.

Step 4: Messages arrive on one device but not another

If you have an iPhone and another Apple device such as an iPad, Apple says to go to Settings > Apps > Messages > Send & Receive on each device and choose the phone number or email address you want to use. If your phone number does not appear, Apple says you can link your iPhone number to your Apple Account or set up Text Message Forwarding. Both have their own Apple articles.

Apple notes that if you use both a phone number and an email address with Messages, you may get separate threads with the same contact, and you can set one as your primary.

Step 5: Fix Waiting for Activation or sign-in errors

If iMessage or FaceTime will not activate, Apple's separate article gives a sequence.

Before you start

• Connect to cellular data or Wi-Fi, update iOS, and check that your time zone is correct under Settings > General > Date & Time.
• Activation uses SMS, which your carrier may charge for. If you see "Your network provider may charge for SMS messages used to activate iMessage and FaceTime," tap Turn On to allow it.

Reset iMessage and FaceTime

1. Go to Settings > Apps > Messages and turn off iMessage.
2. Go back to Settings > Apps, open FaceTime, and turn it off.
3. Restart the iPhone.
4. Turn iMessage and FaceTime back on.

Activate online

1. Go to apple.co/IMFT-mac.
2. Under Enable Apple Account, tap Get Started.
3. Sign in with your Apple Account and follow the prompts. If you use a phone number with iMessage and FaceTime, enter that number.
4. Watch for an email confirming your account is ready.

Use an email address instead

Check the email addresses on your Apple Account, correct any that are wrong, and tap Resend beside the one to verify. Then choose it under Settings > Apps > Messages > Send & Receive.

Be patient with the carrier

Apple says carrier verification can take up to 24 hours. A spinning gear beside your number means the phone is verifying automatically, so do not keep toggling iMessage. Apple also says to contact your carrier to confirm that you can send and receive international SMS, and to wait up to 24 hours after trying these steps.

New iPhone on iOS 26

Apple notes that on a new iPhone with iOS 26, iMessage does not activate automatically if you set up an eSIM later in Settings. Messages may show as Not Delivered, appear as green SMS or RCS bubbles, or come from your email. The fix is to go to Settings > Apps > Messages and turn iMessage off, then on.

Step 6: Check for a blocked account

Apple lists two alerts that point to a block:

An error occurred while activating iMessage or FaceTime.
iMessage or FaceTime Activation Failed. This account is blocked due to reported spam.

If you also received no email after the online activation request, your account is probably blocked and the request to remove the block was not approved. Apple says iMessage and FaceTime are meant for personal communication, not commercial activity or unwanted messages. Even with a block, you may be able to send SMS, MMS or RCS on a cellular plan after turning off iMessage, and you can try your email address with iMessage and FaceTime.

Step 7: Other problems

Group messages

Apple suggests opening the conversation to see whether you left or were removed. You can rejoin only if someone adds you back. You can also start a new group, or delete the conversation and begin a new one. For group MMS, go to Settings > Apps > Messages and turn on Send as Text Message. If you do not see a Group Messaging option, your carrier may not support it.

Photos and videos will not send

Make sure the iPhone has enough storage to receive images and videos. Carriers may set size limits for SMS or MMS attachments. To send smaller files, turn on Send Photo Previews or Low Quality Image Mode under Settings > Apps > Messages. If a full phone is the problem, see iCloud+ storage plans and pricing in the US for ways to free space, and the related guide iPhone AirDrop not working: how to fix it if you are sharing files nearby.

You switched to a non-Apple phone

If your texts from iPhone users never arrive after you moved your SIM to Android, iMessage may still hold your number. Apple says to deactivate iMessage at its deregistration page, selfsolve.apple.com/deregister-imessage.

Verify that it works

Send a message to a contact you know uses an iPhone. A blue bubble means iMessage is active. Open Settings > Apps > Messages to confirm that iMessage is on and that Send & Receive shows the phone number you chose. If a message is still green, ask the other person to check that iMessage is on and that they are online.

When to contact Apple or your carrier

Apple says that if iMessages still will not send or receive, contact Apple Support, and that if SMS, MMS or RCS still will not work, contact your carrier. Note the exact alert text, whether the problem affects one contact or all of them, and the steps you have tried.

Checklist

• Know that green means RCS or SMS/MMS, which is normal for non-Apple recipients.
• Update iOS, check your connection, and make sure your phone line is on in Settings, Cellular.
• Turn iMessage off and on under Settings, Apps, Messages.
• Choose your number under Send & Receive.
• Turn on Send as Text Message for fallback.
• For Not Delivered, tap the red exclamation point, Try Again, then Send as Text Message.
• For activation problems, check Date & Time, reset iMessage and FaceTime, then activate online.
• Wait up to 24 hours for carrier verification before repeating steps.
• If you moved to another phone, deactivate iMessage.

References

• Apple Support, If you can't send or receive messages on your iPhone or iPad
• Apple Support, If you can't turn on or sign in to iMessage or FaceTime on your iPhone
• Apple Support, Why are my iPhone messages green?
• Apple Support, What is the difference between iMessage, RCS, and SMS/MMS?