Can’t use iMessage or cellular data away from home or any other WIFI

Hello @ashtkelly, we're happy to help with troubleshooting options for your devices cellular data. 

We recommend checking the network strength if your device is experiencing disruptions. The Signal Bars display the connection strength. The more bars that are displayed, the better the connection. When connected to 4G LTE, the LTE icon will be displayed in the Notification bar.

• Note: To view the locations AT&T voice and data service can be used, see the AT&T Network coverage map. 

Mobile data is on by default. Turning off the mobile data will not allow any data to be transferred over the wireless network. Wi-Fi access, voice function, and standard text messaging are still allowed. You can also turn data on/off using your myAT&T account. 

• Select Network & Internet > Select Mobile network>Select the Mobile data switch to turn it on and then off> then select Mobile networks and confirm connection. 
• Quickly turn on and off Mobile Data: Swipe down from the Notification bar, then select the Mobile data icon. Select the Mobile Data switch to turn it on or off
• If you haven't already, please reset your network settings, go to Settings App> General > Reset > Reset Network Settings to refresh your network connection. Check your wireless usage to confirm data on your plan.

You can find detailed instructions for using the iMessage option on your device. Select your make and model and then follow the instructions. If you are still unable to use your iMessages after troubleshooting your data, reach out to Apple support for assistance. If your device was replaced and you are having disruptions, you will need to reach out to Apple support for assistance.

For additional step by step troubleshooting for your mobile data visit our Device support page and sign in for personalized solutions. Make sure your devices make and model are selected and then click "Go". Meet us back here with the resuts of the troubleshooting tool if you still have questions. Thank you for contacting AT&T Community Forums. 

Alasani, AT&T Community Specialist