CNET/Sarah Tew

CHICAGO -- Sprint is so confident that the hard work it's put in over the past couple of years to improve its network is bearing fruit that it's offering customers a 30-day money-back guarantee for trying the service.

Sprint made this announcement and a slew of others at an event Monday here at the Museum of Broadcast Communications. In addition to the money-back guarantee, the company announced that as of today it's offering nationwide high-definition voice service, which 16 million Sprint customers with HD-ready devices can start experiencing today. Additionally, the company said it has deployed its 4G LTE service in 28 markets and is now reaching 250 million potential subscribers with the faster wireless service.

It also announced an extension to its "Framily" service called Framily Wall, which allows any Sprint customer to create a private social network of close family and friends to share messages, pictures, calendars, location, and more information with each other. Framily is the name that Sprint uses for its friends and family service plan, which offers discounts on service for people who share a new kind of family plan. The Framily plan is very popular, CEO Dan Hesse has said. And it's designed to build loyalty among its customers.

Now, Sprint is expanding the Framily brand and using it to create a platform on which the company can add new services. As a result, the Framily Wall is available not only to Framily subscribers, but also to other Sprint customers free of charge. The app developed by Family & Co. is for anyone who wants to create a smaller, private social network to communicate with friends, family, or coworkers also using the Sprint network. A premium service is also available for $2.99 that offers more cloud storage.

Sprint also announced it's the exclusive carrier for Samsung's new Galaxy S5 Sport, a water- and dust-resistant version of the flagship Galaxy S5 launched earlier this year. Sprint is using the Galaxy S5 Sport to highlight a new fitness feature coming to all Android phones later this year called Fitness Live, which consolidates and provides a richer experience for a slew of fitness apps and devices.

Additionally, Sprint announced that it is expanding Wi-Fi calling to the Samsung Galaxy S5. The company announced in February it would support Wi-Fi calling on a couple of handsets. The GS5 will be the latest to get the functionality through a software update. The feature allows GS5 users to make calls and send text messages over registered Wi-Fi networks. Sprint also said the feature will work internationally, allowing Sprint customers to make free Wi-Fi phone calls using their existing US phone numbers to 100 countries around the world. Sprint's network acts as the cellular backup network for Wi-Fi first calling networks, such as Republic Wireless.

Sprint's flood of announcements Monday are meant to show that the ailing wireless carrier, which is the third-largest operator in the nation, is getting its mojo back. The company, which is rumored to be in talks to acquire rival T-Mobile, has had a difficult couple of years as it upgraded its network to a brand-new architecture as part of its Network Vision and Spark programs. Network Vision is a program in which the carrier is ripping out old infrastructure and replacing it with newer, more flexible network gear that will make it easier to upgrade to new network technologies in the future. At the same time, the company has been building its Spark LTE 4G network, which is a program for reusing existing spectrum that Sprint owns as well as spectrum from its Nextel acquisition and Clearwire purchase.

Hesse admitted at the end of 2013 that there had been some growing pains as Sprint went through this upgrade process. And he promised that the worst was behind the company. He said that 2014 would be the year customers noticed major improvements.

"We are turning the corner in terms of quality on the network," he said during the company's presentation Monday.

In an interview with CNET, he said that the company has finished phase one of its network upgrade, which includes the HD voice enhancements and expansion of its 4G LTE network using its 1,900MHz Sprint spectrum. And the company is already working on the next phase of the deployment, which is expanding the 4G LTE network using 800MHz spectrum it bought from Nextel, as well as 2.5GHz spectrum it bought from its former partner Clearwire.

Also as part of the upgrade, Sprint has quadrupled the number of transmitters it's using to improve the coverage and strength of its wireless signals. And in lab testing, the company is seeing improved coverage in urban areas of 25 percent. In suburbs, coverage is improving to 50 percent and in flat rural terrain coverage can be improved by as much as 70 percent.

Hesse said these improvements, which are starting to manifest now, will give consumers a much improved experience, not only for voice but also for data services.

"This is why we announced the money-back guarantee," he said. "People will notice the improvement in the voice network and that LTE is widely available. We want them to give us a try. The network is substantially better than when we started this upgrade."

Still, Hesse admitted that there's more work to be done. And he said the company is busy making those improvements. He also hinted that the company could be starting a major marketing campaign soon that will get the word out about Sprint's improved network.

When asked if the company was planning a media blitz similar to marketing campaigns launched by its rival and potential takeover candidate T-Mobile, he smiled and said, "Stay tuned."