An NGN (Next Generation Network) architecture in figure below is a universal multi-service network designed for the transmission of voice, images and data on a packetswitching basis. An NGN provides the qualityof service necessaryf or different types of telecommunication traffic. Characteristically, the transmission and the routing of the packets and the elements of the transmission equipment (links, routers, switches, gateways) are physicallyand logicallyseparat ed 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 telephony to data, image, multi-media, broadband and management applications. NGN Architecture is based on four layers:

• Access Layer
• Transport Layer
• Control Layer
• Application Layer

These features represent the basis for drawing a distinction between an NGN and an ordinaryt elephone 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.
• 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.