If you’re one of T-Mobile’s iPhone-toting customers, you won’t notice any major new features, but there are several bug fixes in tow. iOS 8.3 brings new emoji to the keyboard, Siri in a few new languages as well as equipping the digital assistant with a new feature: The ability to initiate a phone call on speakerphone.
Bug fixes include a wide range of issues, ranging from general stability and performance to third-party keyboard performance, Wi-Fi, Bluetooth and almost everything in between.
I just checked my settings and found the update waiting there. If you have a compatible iPhone or iPad, check for updates and you should be able to download and install it immediately.