Researchers from the University of Washington have developed the very first battery-free phone. Its sound quality is pretty shitty, but imagine not having to charge your phone because it harvests light and radio waves from your surroundings. Sweet.

“We’ve built what we believe is the first functioning cell phone that consumes almost zero power,” co-author Shyam Gollakota, an associate professor in the Paul G. Allen School of Computer Science & Engineering at the UW told the University of Washington blog.

The researchers used a nifty way to get rid of the most power hungry part of normal cell phones: The conversion of analog audio signals into digital data. According to the post on the University website, “this process consumes so much energy that it’s been impossible to design a phone that can rely on ambient power sources.”

To get rid of that part of the process, the researchers devised a way to use the tiny vibrations of the phone’s microphone and speaker to encode incoming and outgoing signals. Sadly enough, this doesn’t allow the phone to simultaneously send and receive audio. Instead, the caller has to hold in a send or receive button while sending or receiving. In that sense, it’s more similar to a walkie-talkie than a real cell phone.

At the moment, the cell phone harvests its energy from radio signals sent out by a special base station and a tiny solar cell it has on board. But the researchers state that their base stations could be installed in cell towers and Wifi routers, to allow for the mobility we’re used to from our normal, boring, battery-powered cell phones.