Written by: Magnus Fyro, Kai Heikkinen, Lars-Göran Petersen and Patrik Wiss
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The telecommunications community is migrating toward a new network architecture based on horizontal layers. Call control and connectivity, which have traditionally been bundled in telecommunication networks, are being separated into different layers. The connectivity layer is based primarily on asynchronous transfer mode (ATM) and Internet protocol (IP) transmission. Access networks and the core network are parts of the connectivity layer. The connectivity layer provides interfaces to legacy networks, such as the public switched telephone network (PSTN). The layered architecture is being deployed in third-generation mobile networks—that is, the universal mobile telecommunication system (UMTS). Ericsson has taken an active role in promoting this new architecture in relevant standardization bodies. Media gateways (MGW) have been introduced to bridge between different transmission technologies and to add service to end-user connections. Smooth step-by-step migration toward the new network architecture is achieved by splitting the mobile services switching center (MSC) and the serving GPRS support node (SGSN) into a media gateway and servers. The authors describe the role of the media gateway in third-generation mobile networks, and present Ericsson’s new media gateway product, which is based on the Cello packet platform.
[First published in Ericsson Review no. 04, 2000]