https://wccftech.com/ios-12-1-3-fixed-my-biggest-cellular-related-gripe-on-iphone-and-ipad/

The changelog didn’t say much, but iOS 12.1.3 turned out to be a bigger deal for me on the iPhone and iPad both. It should for you as well.

I’ve been a long time user of the iPhone. In fact, I jumped onto the iOS bandwagon when the iPhone 4 was nearly ending its lifecycle and I never turned back, subsequently upgrading to every year to the latest and great from Apple. Fanboy alert.