Carrier settings updates are small files that are installed on smartphones and iOS devices. The Carrier settings include updates to Access Point Names (APNs), MMS Settings, and data for tethering and some stock iOS apps. If you don’t have the most up to date Carrier Settings, your phone may work slower or not at all in certain locations.
Step-by-step instructions to update your carrier settings on your iPhone or iPad
Carrier settings updates let your mobile carrier update network and related settings to activate or improve cellular network connectivity and performance.
When a carrier setting update is available, you will generally be prompted to update your device with it. If it’s a mandatory update, you’ll see the “OK” dialogue button instead of “Update” to let you know that the new settings were downloaded and installed.
To manually check and/or install a carrier settings update, do the following:
Connect to a Wi-Fi or cellular network.
Tap Settings > General > About. If an update is available, there will be an option to update the carrier’s settings.
To see the carrier settings version on your device:
Tap Settings > General > About and look next to Carrier.
Anytime a new SIM card is inserted into your iPhone or iPad, you’ll need to download the latest carrier settings for your new carrier to work.