Check for iOS and Carrier Updates

Make sure you’re running the latest available iOS version, as new releases sometimes improve network connectivity.

The same is also true for releases from your mobile provider. While these are less frequent and should normally be pushed down automatically, you can check if there’s a new release from your provider and install it by going to Settings > General > About. You can see the version number under your cellular settings, and you’ll be prompted to install a carrier update if one is available.