Service providers or enterprises can develop a Voice over IP architecture in one of three ways:
—By IP-enabling an existing telephony network
—By voice-enabling an existing IP or other packet network
—By building a pure IP telephony network from scratch
Regardless of a service provider gets to a Voice over IP architecture, the end result is the same. Whether the network is a pure IP network or uses other existing packet infrastructure, the architecture will have these elements in common: Communication server—Also called a "call server" or "softswitch," this element is the brains of the network, providing call control, gateway control, service intelligence, and other centralized functions. Signaling point—This element enables the Voice over IP network to communicate with the SS7 (Signaling System 7) network. Line and trunk gateways—These elements provide connectivity to the public network (either the local line or long-haul trunking segments, respectively) Core switches and routers—These elements keep traffic moving through the core of the IP network Application server—This element provides voice, data, or multimedia services from a central location in the IP network.
