1st SYNC with laptop after just switching from ATT to T-Mobile AND iTunes dialog pop up box asks "An update to the carrier settings for your iPhone is available. Would you like to download it now?" ...so should I download it...or will that download mess up my NEW T-Mobile service??
Best answer by snn_555
Yes, to make the most use of fixes and function, update your carrier version for use on T-Mobile.
Carrier settings updates let your carrier provider update carrier network and related settings to improve cellular network connectivity and performance or add support for features like VoLTE or Wi-Fi Calling. For more information on what is included in a carrier settings update, contact your carrier.
When a carrier setting update is available, you will be prompted to install it. If your carrier releases a mandatory update, you'll see an OK button instead of an Update button to let you know that the update was downloaded and installed.