Cellular data is Turned off for “iMessages”. How to re-enable

iOS prompted a system notification “cellular data is Turned off for “Message”

Now I can only send txt iMessage, iMessage with attachments are totally not functioning.

Any one know how to turn on cellular data for IMessage?

I tried followings , but all failed to fix the issue

1) reset network settings.

2) logout iMessage ID and re-login

3) logout iCloud ID and re-login