echnology and are premised on the fact that the circuit switched TDM network will slowly be replaced with packet switched (IP and/or ATM) infrastructure. The softswitch architecture was developed to facilitate this migration, basically offloading voice from circuit infrastructure onto the packet environment. The softswitch architecture essentially un- bundles and distributes the circuit switched functionality across the packet backbone. The design philosophy behind the softswitch is to create a distributed and scalable software system, independent of a specific underlying hardware and operating system. Circuit-Switched Softswitched IIIII Feature Media Server Server Protocols Back Office Signaling Gateway and APIs Applications Services & Applications Media Gateway Controller Controller Protocols and APIs Media IP/ATM Gateway Backbone Switching IP/ATM Figure 34. Circuit-Switched VS. Softswitched Architecture Chapter 8 - Next-Generation OSS The softswitch architecture consists of multiple components: Media Gateway, Media Gateway Controller, Signaling Gateway, Feature Server and Media Server. Media Gateway: Media Gateways (MGs) are devices that actually implement the switching function between the TDM infrastructure and the packet/cell protocols. An MG is essentially a low-level protocol translator that converts TDM flows into packet flows and vice versa. The MG appears as a circuit-switched device to the circuit-switched network on one side and a packet/cell switch to the packet network on the other side. MGs may connect to a PSTN end-office with a line-side interface or to a PSTN tandem switch with a trunk-side interface. The other trunk side of the MG will always be an interface to the packet/cell network. Media Gateway Controller: The Media Gateway Controller (MGC) is often also referred to as the "softswitch." MGC implements the call control function, outside of the switching fabric (MG) and hence the distributed nature of the softswitch architecture. MGCs are connected to MGs on one side and to feature and medi