ystems control basic operations, including how information gets on and off the network, how it's organized in memory, and the administrative interface IP Private Branch Exchange Architecture for staff members to monitor and maintain the system. System administration and programming is performed via a computer logged in to the communications server. In addition to basic voice features and call processing, some communications servers also hold software for specialized applications, such as audio and video confer- encing, speech recognition, contact centers, voicemail, and Unified Communications (UC) systems. In other instances, these applications might be on separate application servers. Whether they reside on separate servers or in the communications server, any device connected to the corporate LAN-even those at remote locations-can be given permission in the communications server to access these applications. Redundant Communications Servers for Backup Many IP phone systems are equipped with two communications servers for redun- dancy, in case the main server crashes. If the primary server goes down, the system will automatically fail over to the backup and continue to process calls. In addition, communications servers at different sites can provide mutual redundancy. If the server at one site fails, traffic is sent over the data network to the backup site. This assumes that the link to the remote site has adequate capacity to support the additional traffic. If the entire network fails at one site, the telephone company would have to be notified to forward calls to the backup location. Media Gateways, Protocol Translation, and Signaling Media gateways contain Digital Signal Processors (DSPs) that compress voice data to make it smaller and more efficient to transmit. DSPs also convert analog voice signals to digital, and vice versa. They then bundle the digital voice signals into packets com- patible with LANs. In addition, media gateways include circuit packs with ports for connections to traditional circuit-swi