In certain embodiments, a web services system receives a request to provision a device, such as a telephone, as an authentication device. The web services system initiates display of an image communicating a key to allow the telephone to capture the image and to send key information associated with the key. The web services system receives the key and determines that the key information is valid. In response to the determination, the web services system sends a seed to the telephone to provision the telephone to be an authentication device. The telephone can use the seed to generate one-time passcodes to access a service of the web services system.