Previously available only to Windows Phone 8 users on Verizon Wireless in the United States, the useful Data Sense feature is now being deployed more broadly to users who upgrade to the GDR2 update. The downside: Some carriers, including AT&T, have chosen to block this feature.

Note: This is an excerpt from my free eBook, Paul Thurrott's Windows Phone 8.

Data Sense app helps you track your cellular data usage. This is particularly important because most people do not have unlimited data connections, but instead have what’s called a metered account, where you are allotted a certain amount of data each month and are charged extra if you exceed that usage.

Note: Data Sense isn’t currently available via all wireless carriers. If you don’t see Data Sense on your phone, most wireless carriers do offer an alternative. For example, AT&T Wireless offers a myAT&T app that provides similar functionality.

You can launch Data Sense from the All Apps list, of course, but chances are you’ll want to pin it to your Start screen because its tile provides live updates about your data usage. This is explained below.

Configure Data Sense on first use

The first time you run Data Sense, you’re prompted to set it up for the particulars of your data plan so that it can provide accurate real time information about your usage.

Tap Yes. In the next screen, you’re prompted to enter your data limit type, which can be one time, monthly or unlimited. For most people, this will be monthly.

Tap Done after you’ve made a choice. Then, new options appear.

If you’ve chosen a Monthly limit type these options include:

Monthly reset date. This is the day of the month at which your wireless plan switches over to the next billing month.

Monthly data limit and Units. These two fields will include a number (Monthly data limit) that, combined with Units, determines your monthly data limit. For a 1 GB monthly limit, for example, you could enter 1 for Monthly data limit and GB for Units.

Understand Data Sense

Once you’ve configured Data Sense for the first time, you can use the app. It’s simple enough, with just two views you can pivot between. The default view, Overview, provides a peek at your data usage for the current billing cycle.

The Usage view explains your total data usage—over both cellular data and Wi-Fi—and displays a list of the apps you’ve used along with their accompanying data usage. This can help you find any apps that are particularly heavy data users.

Find nearby Wi-Fi connections

Hidden in the Data Sense UI is a very useful feature: You can find nearby Wi-Fi connections using Bing Maps. This is particularly helpful when you’re trying to minimize your cellular data usage, either because you have a low monthly limit or are reaching the limit and would like to conserve the bandwidth. To utilize this feature, navigate to More (“…” in the app bar), and then Map Nearby Wi-Fi.

Bing Maps will appear—yes, even on Nokia handsets—and display your position on the map. Around you, you will see black flags, each of which represents a nearby Wi-Fi hotspot.

You can tap a flag to view basic information about the hotspot on the flag itself.

Or, tap it again to see even more information.

If you’re in range of the hotspot, you can use Wi-Fi Settings (Settings, System, Wi-Fi) to connect and give your cellular data connection a rest.

Configure Data Sense

While Data Sense prompts you to configure your data limit the first time you launch the app, you can visit Data Sense Settings later to make changes. But this interface offers another useful option: You can restrict the use of background data when you’re near your data limit. It’s enabled by default, but it’s worth checking to make sure. To do so, tap the Settings app bar button.

Use the live tile to track data usage

While the Data Sense app is useful, oftentimes you won’t need to open it, as its live tile displays how much cellular data is still available in the current billing period. The tile animates between this information and a stock graphic, so you might have to wait a moment.

Paul Thurrott's Windows Phone 8 is a free eBook and my gift to the Windows Phone community. --Paul