CaaS is a terminology given in telecom industry as Communication as a Service.
The Voice-over-Ip (VoIP) follows a same delivery model.
CaaS can offer the enterprise user features such as desktop call control, presence, unified messaging, and desktop faxing.
In addition to the enterprise features, CaaS also has a set of services for contact center automation that includes IVR, ACD, call recording, multimedia routing (e-mail and text chat), and screen pop integration.