This white paper is an introduction to the terms, characteristics, and services associated with internet-based computing, commonly referred to as cloud computing. Characteristics, such as infrastructure, provisioning, network access, and managed metering are presented. The primary business service models being deployed (such as software, platform, and infrastructure as a service) and common deployment models employed by service providers and users to use and maintain the cloud services (such as the private, public, community, and hybrid clouds) are discussed. Also introduced are the benefits and challenges associated with cloud computing, and for those seeking to use communications services in the cloud, briefly presented are different ways of determining the interfaces needed to use these communications services. Cloud Computing The term “cloud”, as used in this white paper, appears to have its origins in network diagrams that represented the internet, or various parts of it, as schematic clouds. “Cloud computing” was coined for what happens when applications and services are moved into the internet “cloud.” Cloud computing is not something that suddenly appeared overnight; in some form, it may trace back to a time when computer systems remotely time-shared computing resources and applications. More currently though, cloud computing refers to the many different types of services and applications being delivered in the internet cloud, and the fact that, in many cases, the devices used to access these services and applications do not require any special applications. Many companies are delivering services from the cloud. Some notable examples include the following.