iMessage not working with activation error

iMessage activation errors usually come from network issues, SIM problems, etc. Try: turning iMessage off/on, resetting network settings, checking for carrier SMS issues, signing out/in of Apple ID, and verifying your phone number is registered. If still failing, your carrier may need to reset SMS activation for your line.

To troubleshoot a non-working iMessage, first check your network connection, ensure iMessage is toggled on in Settings > Messages, and restart your iPhone. If that doesn't work, try signing out of and back into your Apple ID, checking your date and time settings, and verifying your phone number is registered in Settings > Messages > Send & Receive.