An NGN(Next Generation Network) is a universal multi-service network designed for the transmission of voice, images and data on a packet switching basis. Its network seamlessly blends the public switched telephone network (PSTN) and the public switched data network (PSDN), creating a single multiservice network. Rather than large, centralized, proprietary switch infrastructures, , this next-generation architecture pushes central-office (CO) functionality to the edge of the network.

An NGN provides the quality of service necessary for different types of telecommunication traffic. Characteristically, the transmission and the routing of the packets and the elements of the transmission equipments ( links, routers, switches, gateways) are physically and logically separated from the devices and the intelligence controlling the execution of calls and services. The network intelligence supports all types of services in the packet network, from basic voice telephone to data , image, multi-media, broadband and management applications. These feature represent the basis for drawing a distinction between an NGN and an ordinary telephone and IP network, which otherwise prevail in telecommunications. An NGN, the result of merging the internet with the telephone network, combines the best features of both. It provides:

• Adaptability for transmitting any type of traffic, which can be compared to the internet’s adaptability as opposed to the inefficiency of a PSTN in transmitting data( this fact is especially important with regard to the estimation that data will soon represent 90% of telecommunication traffic).
• Guaranteed quality of voice telephony services and critical data applications; in this case an NGN offers PSTN reliability as opposed to the best effort of the internet’s capacity.
• Low transmission costs per content unit- the price is closer to the internet than to a PSTN, the total amount of data and voice traffic trebles every year.