Cisco VoIP Structure

The OSI reference model was designed to create standard methods of connecting and communicating across data networks. In the realm of voice, similar connection models exist to describe voice communications. Cisco has developed a type of model to describe the Unified Communication System.

Cisco Voice Unified Communications Layers

Endpoints Layer	IP Phone, Wireless/Cell phone, Video Phone, IM Client
Applications Layer	Voice Mail, Conference Call Apps, Call Center Apps, 911 Services
Call Processing Layer	Unified Communications Manager, Unified Communications Manager Express, UC500
Infrastructure Layer	ASA Firewall, Voice Router/Gateway, Voice Switch

While the layers work together to create a functional voice network, each layer performs unique functions to the voice network.