I'm having trouble setting up my Cellular Data

Check your iPhone settings

Go to Settings and turn on Airplane Mode, wait five seconds, then turn it off. Check Do Not Disturb. Go to Settings > Focus > Do Not Disturb and make sure it's turned off. Check for any blocked phone numbers.

If you can't make or receive calls on your iPhone - Apple Support

Can't send or receive message then try these steps first

1. Restart your device: ... 
2. Check your network connection. ... 
3. Check with your carrier to see if the type of message you're trying to send, like MMS or SMS, is supported.
4. If you're trying to send group MMS messages on an iPhone, go to Settings > Messages and turn on MMS Messaging.

More items...•

If you can't send or receive messages on your iPhone, iPad, or ...

If you are unable make a call or receive; If you can't make or receive calls on your iPhone - Apple Support

Cellular Update Failed —> If you see an Update Failed or Apple Pay Not Available alert after iOS update or restart

Settings > Mobile Data > APN [under Mobile Data APN] enter the APN pin

View and edit your APN settings

If your carrier allows it, you can view your APN settings in one of the following locations: Settings > Cellular > Cellular Data Options > Cellular Network. Settings> Mobile Data > Mobile Data Options > Mobile Data Network.

View and edit your Access Point Name (APN) on your iPhone ...

Carrier Update (Required): Released by your Cellular Service provider (Carrier Update), affects your Outgoing / Incoming calls, SMS, Data etc..

How to Update Carrier Settings

You can manually check for and install a carrier settings, update with these steps: Make sure your device is connected to a Wi-Fi or cellular network. Tap Settings > General > About. If an update is available, you'll see an option to update your carrier settings.

Update your carrier settings on your iPhone or iPad - Apple Support

If nothing helps then --> If you see a Cellular, Ultra Wideband, or Apple Pay Issue message after an iOS update or restart

Reset Network Settings: Only network settings are removed.

• When you reset network settings, previously used networks and VPN settings that weren’t installed by a configuration profile or mobile device management (MDM) are removed. Wi-Fi is turned off and then back on, disconnecting you from any network you’re on. The Wi-Fi and Ask to Join Networks settings remain turned on.
• To remove VPN settings installed by a configuration profile, go to Settings > General > Profiles & Device Management, select the configuration profile, then tap Remove Profile. This also removes other settings and accounts provided by the profile. See Install or remove configuration profiles on iPhone in this guide.
• To remove network settings installed by MDM, go to Settings > General > Profiles & Device Management, select the management, then tap Remove Management. This also removes other settings and certificates provided by MDM. See “Mobile device management (MDM)” in the iOS Deployment Reference.
• Reset your Network Settings. Tap Settings > General > Reset > Reset Network Settings. This also resets Wi-Fi networks and passwords, cellular settings, and VPN and APN settings that you've used before.

If the above fails...

Reset All Settings: All settings—including network settings, the keyboard dictionary, the Home screen layout, location settings, privacy settings, and Apple Pay cards—are removed or reset to their defaults. No data or media are deleted.

1. Reset All Settings: Return iPhone settings to their defaults - Apple Support:- Return iPhone settings to their defaults
2. You can return settings to their defaults without erasing your content.
3. If you want to save your settings, back up your iPhone before returning them to their defaults. For example, if you’re trying to solve a problem but returning settings to their defaults doesn’t help, you might want to restore your previous settings from a backup.

If nothing above works probably it could be your iPhone may have a radio or antenna problem. In that case, take your device to an Apple Retail Store or Apple Authorized Service Provider, or contact Apple Support and get the hardware tested and if needed repaired/replaced.

Find Locations - Location Selector - Apple

Contact Apple for support and service - Apple Support 

Get a Genius Bar Reservation and Apple Support Options - Apple

Contact Genius Bar. Manage Reservations - My Reservations - Apple

To ensure a smooth and uninterrupted mobile experience with your iPhone, it is essential to follow two crucial steps:

1. Check for a Valid SIM Card:
   1. Having a valid SIM card is necessary for your iPhone to connect to your carrier's network and make calls, send messages, and access mobile data. To confirm that you have a valid SIM card, follow these steps:
   2. Insert or Replace the SIM Card: Locate the SIM card tray on your iPhone (usually on the side of the device). Use the ejector tool or a paperclip to open the tray. If there is no SIM card or the existing one is damaged, insert a compatible and activated SIM card provided by your mobile carrier. Ensure that it's properly placed in the tray and gently close it.
   3. Check SIM Card Activation: If you recently received a new SIM card or made changes to your plan, ensure that the SIM card has been activated by your carrier. You can do this by checking your carrier's website or contacting their customer support.
2. Ensure Cellular Coverage:
   1. To use cellular services like calling, texting, and mobile data, you need to be within an area with cellular coverage. Here's what you can do to verify that you are in an area with cellular coverage:
   2. Check Signal Bars: Look at the signal bars displayed in the status bar at the top of your iPhone's screen. More signal bars generally indicate better coverage. If you have no bars or low signal strength, you might be in an area with weak or no cellular coverage.
   3. Disable Airplane Mode: If Airplane Mode is enabled, it turns off all wireless communication, including cellular. Disable Airplane Mode by going to Settings > Airplane Mode and toggling it off.
   4. Check Carrier Coverage Map: Visit your carrier's website and access their coverage map to see if your current location is within the covered area. Remember that coverage can vary depending on your carrier and your location, so it's a good idea to check this before traveling to a new area.
   5. Restart your iPhone: Sometimes, network-related issues can be resolved by simply restarting your iPhone. Press and hold the power button (or side button) until the "slide to power off" slider appears. Slide it to turn off the device and then turn it back on after a few seconds.
   6. Try Another Location: If you are experiencing poor or no cellular coverage, move to a different location or go outside to see if the signal improves. Sometimes, obstacles like buildings or natural features can interfere with the signal.

By following these steps and ensuring that you have a valid SIM card and are in an area with cellular coverage, you can make the most of your iPhone's capabilities and stay connected wherever you go.

You may get better and prompt responses if you may kindly provide the iPhone Model that you have and the iOS version if it is known to you and re-post.

With the limited information that you have provided, It is hard to even guess the problems faced by you. 

You may get faster and better responses to your query by --> Writing an effective Apple Support Commun… - Apple ...

Please re-post with detail so that someone else can help.