The AuthDirect service architecture is based on a distributed authentication model that uses the Internet to communicate with AuthDirect TollBooth servers. This model allows for quick and inexpensive deployment of service venues using local bandwidth and IP services without the need for dedicated circuits to a centralized server location. The AuthDirect solution's key architecture components consist of an off-the-shelf RADIUS-based Access Control unit resident at the access venue, the secure transport mechanism from the access venue, and TollBooth, consisting of fully redundant servers running the services described below. Roaming is supported via an Internet connection to the appropriate third party realm authority for each roaming user. The diagram above shows how these components are related.