T-Mobile knows it has a hit on its hands with the recently released Nokia Lumia 521. The smartphone is still sold out online and at most Walmart retail stores. T-Mobile will begin offering the smartphone online and in its retail stores beginning tomorrow for $150, or if you're lucky and can score one at Walmart the price drops to $130. T-Mobile has just made the Nokia Lumia 521 smartphone the first Windows 8 smartphone that supports the very popular Wi-Fi calling feature.

The Nokia Lumia 521 is a great entry level Windows Phone. I've been using one for a few days and have been very impressed by this contract-free smartphone. When I heard about the T-Mobile Wi-Fi calling firmware update, I wanted to see what the experience would be like on a low-end, prepaid smartphone and how good the quality would be.

If you have a Nokia Lumia 521 and haven't received a notification for a system update, you can manually pull the update. To do this go to the Settings app, scroll down to 'phone update', tap  'check for updates', follow the on-screen prompts, and wait until your Lumia 521 reboots a few times.

Since this is a major update the Lumia 521 will be Master Reset, which means you'll want to create a backup of your Lumia 521. T-Mobile recommends making a backup of your device and provides simple instructions on how to do so. Once the update was finished on the Lumia 521, I restored the backed up files and the Wi-Fi calling feature was now available.

I was able to try out the Wi-Fi calling feature on the Lumia 521 and calls sounded crisp and clear on both ends. It's great not having to use your minutes at home since you can now make calls over your Wi-Fi network with this update. I don't have the best T-Mobile coverage, so this really extends the usefulness of this inexpensive smartphone. This is a great feature for anyone looking for a budget smartphone that will allow you to save your minutes by using Wi-Fi for your calls, plus you get a great inxpensive Windows Phone 8 smartphone.