• PLATFORM AS A SERVICE (PAAS) —
Consumers purchase access to the platforms, enabling them to
deploy their own software and applications in the cloud. The operating systems and network access are not managed by the consumer, and there might be constraints as to which applications can be deployed.
• INFRASTRUCTURE AS A SERVICE (IAAS) —
Consumers control and manage the systems in terms of
the operating systems, applications, storage, and network connectivity, but do not themselves control the cloud infrastructure. Also known are the various subsets of these models that may be related to a particular industry or market. Communications as a Service (CaaS) is one such subset model used to describe hosted IP telephony services. Along with the move to CaaS is a shift to more IP-centric communications