Network convergence refers to using packet network to conduct voice (telephony), video and data services, and phasing out the traditional circuit switched PSTN (Public-Switched Telephone Network) gradually. The migration process from two separate data and voice to finally a complete converged packet network carrying both voice and data services may take decades to finish. The driving forces behind such migration are cost saving, operation efficiency and new services deployment.

Voice over Internet Protocol (VoIP) was first introduced as a possible application for carrying voice conversations over the Internet in 1990. Over the past decade, the technology has improved dramatically, and standards have been created to support commercial use of voice over packet. The most popular standards are: SIP, H.323, MGCP, Megaco, etc. Deployment of VOIP solutions in both enterprises and service providers are taking off.

The traditional multiple physical networks and overlay networks are designed with a single use in mind: traditional LAN traffic, voice or video transport, or storage extension. With ever increasing application and service demands, service provider and enterprises are constantly adding bandwidth or network capacity to all of these networks -- what works well in parts becomes inefficient as a whole. Meanwhile, projects to consolidate server or storage resources are full of compromises, performance uncertainties, and hidden costs. This becomes the single most critical challenge, which takes lots of investment and time to resolve.

Service Provider's networks are in the process of network convergence

Related Terms：PSTN, VOIP and Protocols, SIP, H.323, MGCP, Megaco