s with www.TechnicalPDF.com extension numbers and permissions. Permissions include specifying who is allowed to use particular features such as video conferencing and placing calls to international locations. Most IP servers run on UNIX, Linux, or Microsoft's Windows operating systems. These operating systems control basic operations, including how information gets on and off the network, how it's organized in memory, and the administrative interface 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 conferencing, 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. 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 compatible with LANs. In addition, media gateways include circuit packs with ports for connections to traditional circuit-switched analog and digital trunks. Media gateways are responsible for managing some security, monitoring call quality, detecting and transmitting off-hook conditions, and handling touch- www.TechnicalPDF.com tone, dial tone, busy signal, and ring-no-answer conditions. Media gateways transmit signals for VoIP such as ringing, call setup, and touch-tone in separate channels from voice calls. In IP telephone systems, the gateways a