[header] How to update carrier settings on an iphone [title] Connect to a wi-fi or mobile network. [step] Your iphone must be connected to the internet to access to download the file that contains your new carrier settings. [substeps] 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.