T-Mobile just became the fourth US carrier to send the Android 4.4 KitKat update out to Samsung Galaxy S4 users.

The Galaxy S4's KitKat update began rolling out to T-Mobile customers over the air today.

Users can also download the smartphone management program Samsung Kies and install the update manually through their PCs.

Your move, Verizon

Sprint was first out of the gate with the Galaxy S4's KitKat update, followed by US Cellular and AT&T.

Of the biggest US carriers, that leaves only Verizon lagging on the S4's 4.4; Big Red has yet to announce plans for the phone's OS upgrade.

KitKat includes a number of improvements to Android, including speed upgrades, new productivity options and expanded Google Now functionality.

Via Android Community