The Switzerland-based company launched an Android app Tuesday that allows users to call each other using their mobile phones' data connections without building a new contact list or setting up a username.
After users install the app, their phones automatically use Voxtrot's free service when they dial other Voxtrot users. If the person a user is calling doesn't also use Voxtrot, the phone makes the call using the regular carrier. The service works anywhere in the world with whatever type of data connection is available (Wi-Fi, 3G, 4G, etc.).
Users are automatically connected to Voxtrot whenever they turn on their phones, so there's no need to launch an app in order to make a call through the service. It identifies users by their phone numbers instead of usernames, and this enables dialing and receiving calls to work the same way with Voxtrot as it does with your regular carrier.
Founder Taavet Hinrikus was Skype's first employee and worked with the service that made VoIP a popular phone call alternative for seven years. But he says that services like Skype fall short when it comes to their mobile apps. While it might make sense to build up a list of contacts and use a username on a computer, he says, it doesn't make sense on a mobile phone -- where your best contact list is already loaded and your number identifies you.