Echo lets you transfer data - like contacts, files and URLs - between phones via sound. Sound has several important advantages over sharing via Bluetooth or the Internet.

• Offline: Does not require network access. Useful in planes and villages.
• Quick: Does not require any setup. A Bluetooth transfer would require pairing the devices first. Internet messaging applications like WhatsApp would require you to know the other person's phone number / contact details. With Echo, you just have to be in listening distance.
• One-to-many: With Echo, you can simultaneously send the same data to all phones in range. Useful when sharing your phone number at your first day at work.

With Echo, you can share contact details between phones via sound.

Select a contact, and tap 'Share'. You will see Echo in the options. Ask your friend(s) to open Echo. Your phone will emit a 2-second sequence of tones, while your friend's phone listens. That's it, the contact information is transferred!

Tip: If you want to share your own number with a group of people, simply save your number as a contact, ask everyone to open Echo, and broadcast your number to everyone simultaneously.

Echo converts your URL to a goo.gl shortened URL, and then transfers it via sound. The client app picks up the URL and opens the link on your browser.

Note: Echo is currently buggy.