Signal: An App That Brings Free, Encrypted Phone Calls To Your iPhone

Open Whisper Systems is bringing its security technology to iOS.

Signal: An App That Brings Free, Encrypted Phone Calls To Your iPhone
[Image: Flickr user Marco Bellucci]

Open Whisper Systems, a company specializing in communications tools, has just put out an iOS app that promises users free, encrypted phone calls from anywhere in the world.


It’s called Signal.

“Over the past year, we’ve been working to bring the privacy software we’ve developed for Android to the iPhone,” the company writes in a blog post. The service “will be a unified private voice and text communication platform for iPhone, Android, and the browser,” and will be expanded later this summer to include text.

How safe is it? The company says it uses the ZRTP security protocol (which was invented by cryptographer Philip Zimmermann of PGP fame) built on open source software. The hope is that this will help build a self-policing community of users that can offer improvements.

Try it out here.

Update: An earlier version of this article said Open Whisper Systems was acquired by Twitter five years ago, but I’m told it’s a different entity created after the acquisition.

About the author

Chris is a staff writer at Fast Company, where he covers business and tech. He has also written for The Week, TIME, Men's Journal, The Atlantic, and more.