Your average smartphone user panics at the 20 percent battery alert, watching it drop to 10 percent, then five, then nothing — just a blank, lifeless screen. But researchers at the University of Washington are currently looking into battery-less phones that use ambient radio waves or solar to power the device. While you won’t find a bunch of features packed into the calculator-looking phones, you will be able to place outgoing voice calls via Skype. Much like a walkie-talkie, a button must be pressed for the user to talk to the call recipient. Simple, but effective.

According to CNN Tech, the research team hopes in the near future to encrypt the calls and add a screen to the device.