Sprint today announced a new 30-day satisfaction guarantee, promising to refund device costs as well as waive service and activation fees for any new customers not happy with the carrier.

Sprint previously offered to refund the cost of a device within the first 14 days but customers were still on the hook for prorated service and activation fees.

Sprint’s new offer comes just a few days after T-Mobile’s recently announced seven-day iPhone test drive. Both deals are geared toward getting customers to switch and hopefully stick around.

Depending on which device new Sprint customers choose, nationwide HD Voice could be one of the features they get to test. Sprint today said the service is now available everywhere their network is and that it currently carries 28 prepaid and 33 postpaid smartphones that support the higher-quality voice service. The carrier estimates that 16 million of its customers are currently using HD Voice handsets.

Along with the HD Voice expansion, Sprint announced 28 new LTE markets—bringing its total to 471 covering 225 million people—and three new Sprint Spark markets for a total of 27. Sprint plans to cover 100 million people with its Sprint Spark tri-band LTE network by year’s end, promising average speeds of 6-15 Mbps and peak speeds of 50-60 Mbps. The carrier intends to have 250 million people covered with LTE by mid-2014.

Sprint also said it will soon be deploying 8T8R radios for boosted coverage and speed.

In another move echoing recent T-Mobile announcements, Sprint will now offer Wi-Fi calling and texting in more than 100 countries. Following Apple’s launch of iOS 8, T-Mobile announced that Wi-Fi calling would be available on all its iPhones running the new operating system.

For customers already on Sprint’s Framily plans, the carrier announced a new private social media hub called Framily Wall. The free service will allow Framily customers to make multiple Framily Walls for communicating, organizing and sharing with other Framily plan members. A premium version of the Framily Wall will be available for $2.99 per month and provide 10 GB of Wall storage and support video and voice messages.