Wi-Fi hot spots by Sprint's new service

Sprint is offering a new Wi-Fi calling and messaging service that it says will help improve network coverage for its subscribers, the company announced Friday.

For now, the service, which allows users to make voice calls, as well as, send and receive text messages via a Wi-Fi network when these customers are not in range of Sprint's cellular network, will be available on two Google Android smartphones, the Samsung Galaxy Mega and the Samsung Galaxy S4 Mini. These devices will receive over-the-air software updates to enable the service in the coming weeks. Sprint said it plans to expand the service to additional devices throughout 2014.

Wi-Fi has long been used by wireless carriers and their customers to offload data traffic. AT&T has built large Wi-Fi hot zones in highly trafficked areas as a way to help relieve congestion on its network. Now Sprint is turning to Wi-Fi to improve its voice network coverage. T-Mobile was the first major wireless operator to launch a Wi-Fi voice service to extend coverage of its voice network. Wi-Fi is a useful technology for this since it uses unlicensed wireless spectrum. But there are challenges with the technology as well. It's short-range means that users often must hand-off between multiple networks if they are at all mobile. And the fact that the spectrum is unlicensed means that airwaves can be congested and interference between different Wi-Fi networks is common.Domestic phone calls and text messaging are free using the Wi-Fi service, whereas under certain Sprint plans voice minutes and text messages are counted toward a monthly allotment of activity.

Like T-Mobile, Sprint is also using the existing home, office, and public Wi-Fi networks as a way to improve coverage for Sprint customers. While Sprint's network coverage is considered more extensive than T-Mobile's voice network, the company has always struggled with in-building coverage. The Wi-Fi calling and messaging option should help improve that shortcoming.

Flexing fingertip 3D-prints himself a prosthetic

fter Christian Call suffered an injury on the job and lost the tip of his right index finger, he was determined to find a prosthetic. "Initially I was trying to acquire a life-like prosthetic, but none of them actually worked and the price was out of reach," he told Crave. A few years ago, Call might have simply been out of luck, but advances in consumer 3D printers put him on the path to finding a solution.

Call's journey to create a fingertip started on YouTube. He was browsing and came across a video of a massive 3D printer cranking out plastic wrenches. That got him started on a search for a 3D printer of his own. "I had to have a 3D printer," he said. "I felt that with a 3D printer I could explore a whole new level of creativeness."

An earlier prototype of Christian Call's fingertip design. (Click to enlarge.)

(Credit: Christian Call)

After his injury, Call was let go from his 22-year job and had no insurance. Professionally made prosthetic options were well out of his price range. "I had no idea what a homemade prosthetic would cost but suspected that I could make something for much less than what was offered," he said. He took his skills as a master mechanic millwright and hobby machinist and combined them with his newfound interest in 3D printing.

The prosthetic fingertip was made using an Up Mini 3D printer, a sub-$1,000 machine. When Call squeezes the finger toward his palm, the device moves, so it behaves mechanically like a real fingertip. He created a version that includes a magnet on the tip for picking up metal objects.

Call has been working on the project for a year and a half. "Part of that time was spent wearing my different designs for weeks at a time to work out the problems with them and advance the design," he said. "The function and comfort is quite good. I model the cup part of the prosthetic as close to my actual finger as possible and if need be I can file the pieces for a better fit and function."

Other people in need of a fingertip prosthetic have gotten in touch with Call, and he has worked on outfitting them with his design. He has made other 3D designs available for free on sites like Thingiverse, but doesn't plan for this to be one of them.

He is open to creating prosthetic fingertips for more people, but he encourages them to try the process themselves, and to design and print their own solutions. "Even if it seems too hard to make, you will learn from it and do better next time. This is how I did it," Call said."In the beginning, I saw the attraction to giving away files for recognition and to help fire the interest in 3D printing, but now I think 3D printing needs no help and is surely here to stay," he said. "I feel my time is worth something and if I can help people with my skills and make a little money doing it, then that is what I will do."

Call's DIY philosophy may represent the ultimate fulfillment of the promise of 3D printers. It brings us closer to an imagined future world where 3D printers are as common as paper printers, and people just sit down, design, and create the things they need. The process may take multiple steps along a learning curve right now, but makers like Call are paving the road for widespread use of 3D printers for the greater good, one person at a time.