This article explains what carrier settings updates are and how to use them on iPhone.

A few times a year, your iPhone will let you know that a new version of iOS is available for download by popping up a window on your screen. But every once in a while, you’ll see a message saying there’s a new “carrier settings update.”

To connect to a cellular network, your iPhone must have settings that allow it to communicate with and operate on that network. The settings determine how your phone makes calls, sends text messages, receives data, and accesses voicemail. Each telephone company has its own carrier settings. Carrier settings for your telephone company are added to your iPhone when you activate your phone.

Unlike other settings on your iPhone, carrier settings are hidden from the user and cannot be changed manually.