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How to update carrier settings on an iphone
Connect to a wi-fi or mobile network.
Your iphone must be connected to the internet to access to download the file that contains your new carrier settings.
Use this method when you change network carriers, get a new sim card, or have been instructed by your provider that an update is available.
In most cases, you'll see a pop-up on your iphone when your carrier settings should be updated. If you get such a message, tap update or ok to complete the update.