SMS is turned off in Settings, not in Messages

Text messages on iPhone stop working when SMS (the system that sends regular text messages, not iMessage) is disabled in your phone's settings. This is different from the Messages app itself — the app can be open and working, but SMS won't send or receive if it's turned off at the system level. You turn it back on in Settings under Messages, not anywhere in the Messages app.

The most common reason SMS gets disabled is a recent iOS update, a settings reset, or accidentally turning it off while troubleshooting another problem. The fix takes about one minute and requires no restart.

Key Takeaways

  • SMS is controlled in Settings > Messages, not in the Messages app itself.
  • You need to toggle on "Send as SMS" to receive text messages when iMessage is unavailable.
  • If SMS still doesn't work after enabling it, restart your iPhone and check that cellular data is turned on.
  • Some carriers block SMS on certain plans, so contact your carrier if the setting is on but texts still won't send.

Turn on SMS in Settings

Open Settings on your home screen. Scroll down and tap Messages. Look for the toggle next to "Send as SMS" — it should be green and switched to the right. If it's gray and switched to the left, tap it once to turn it on.

This setting tells your iPhone to send a regular text message (SMS) when iMessage is not available — for example, when you're texting someone with an Android phone or when iMessage servers are down. Without this setting on, your iPhone will try to send an iMessage and fail silently if the recipient doesn't have an Apple device.

Once you've turned on "Send as SMS", close Settings and open the Messages app. Try sending a text to someone. The message should go through as a regular SMS within a few seconds.

Check that cellular data is on

SMS requires an active cellular connection — it doesn't work over Wi-Fi alone. Swipe down from the top-right corner of your screen to open Control Center. Look at the top row of icons. The cellular signal bars should show at least one or two bars, and the airplane icon should not be lit up (gray).

If airplane mode is on (the airplane icon is lit), tap it to turn it off. If you see no signal bars at all, you're out of cellular range — move to a location where you have service and try again. If you have signal but SMS still won't send, restart your iPhone by holding down the power button and volume-down button together until "slide to power off" appears, then slide to shut down. Wait 10 seconds and power it back on.

Verify your carrier hasn't blocked SMS

Some carriers disable SMS on certain plan types, particularly business plans or plans with restrictions. If you've turned on "Send as SMS" and restarted your iPhone but texts still won't send, contact your carrier's customer service. Tell them you're unable to send or receive SMS text messages and ask whether SMS is included on your plan.

Your carrier can see whether SMS is active on your account and can turn it on if it's been disabled. They may need to restart your service on their end, which usually takes a few minutes. Ask them to confirm SMS is working before you hang up, then try sending a test text.

Make sure iMessage is also on (optional but recommended)

iMessage is Apple's messaging system that works over Wi-Fi or cellular data and includes read receipts, typing indicators, and group chat features. It's separate from SMS. You can have SMS on without iMessage, but having both on gives you the most reliable texting experience — your iPhone will use iMessage when possible and fall back to SMS when it can't.

To turn on iMessage, go to Settings > Messages and toggle on "iMessage" at the top. Make sure your Apple ID is signed in — if you see "Sign In" instead of a toggle, tap it and enter your Apple ID email and password. Once iMessage is on, your iPhone will automatically use it for conversations with other Apple users and SMS for everyone else.

Check that Messages app has permission to send SMS

iOS requires apps to have permission to access certain features. If you've recently reset your iPhone or updated iOS, the Messages app might not have permission to send SMS. Go to Settings > Privacy > SMS. You should see "Messages" listed with a toggle next to it. Make sure the toggle is on (green).

If the toggle is off, tap it to turn it on. This tells iOS that the Messages app is allowed to send and receive text messages. After you turn it on, close Settings and try sending a text again.

Restart your iPhone if nothing else works

A restart clears temporary settings problems that can block SMS. Hold down the power button and volume-down button at the same time until you see "slide to power off" on the screen. Slide the power icon to the right to shut down. Wait 10 seconds, then hold the power button again until you see the Apple logo. Let your iPhone boot up completely — this usually takes 30 to 60 seconds.

Once your iPhone is back on, open Messages and try sending a text. If SMS still doesn't work after a restart, and you've confirmed that "Send as SMS" is on and your carrier says SMS is active on your account, contact Apple Support. There may be a deeper issue with your device that requires their help.

Frequently Asked Questions

What's the difference between SMS and iMessage?

SMS is a standard text message that works on any phone and uses your cellular plan. iMessage is Apple's system that only works between Apple devices and uses data instead of your text message limit. Both can be on at the same time — your iPhone chooses which one to use based on who you're texting.

Why would SMS be turned off in the first place?

iOS updates sometimes reset this setting, or you may have turned it off accidentally while troubleshooting. Some people also disable it if they only use iMessage and want to save settings space, though this is rare.

Can I send SMS over Wi-Fi?

No. SMS requires a cellular connection and uses your carrier's network. If you're on Wi-Fi only, iMessage will work, but SMS won't send. If you need to text someone without iMessage, you need cellular signal.

What if I turned on "Send as SMS" but my texts still say "Not Delivered"?

Check that you have cellular signal and that airplane mode is off. If both are on, restart your iPhone. If texts still don't send, contact your carrier — they may need to reset your account or confirm that SMS is active on your plan.

Do I need to pay extra to send SMS?

That depends on your carrier and plan. Most plans include unlimited SMS, but some older or limited plans charge per text. Check your carrier's plan details or contact them to confirm whether SMS is included.