How to Check for a Carrier Settings Update on iPhone
From time to time, your cellular network provider or Apple may issue a carrier settings update to an iPhone or cellular iPad device. The carrier updates are usually very small and make adjustments or improvements to carrier specific settings pertaining to the cell network, data, personal hotspot, voicemail, text messaging, or making calls. While you may see a carrier update pop up randomly on your iPhone, or a request to install one during a general iOS update, you can also manually check for these carrier updates on your own at any time.