The Cisco CallManager is the call-processing software component of the Cisco AVVID (Architecture for Voice, Video and Integrated Data) network. Cisco CallManager software is preinstalled and preconfigured on a server-class, high-availability platform. Cisco CallManager extends enterprise telephony features and functions to packet telephony network devices such as IP phones, software phones, and voice over IP (VoIP) gateways. Cisco CallManager software features a suite of integrated voice applications that perform voice conferencing, manual Web attendant console, click-to-call, and other functions. In addition, a Windows Telephony Applications Programming Interface (TAPI) is available for third-party applications development. The salient feature of all of these basic voice applications is that no additional voice processing hardware is required. Additional data, voice, and video services such as unified messaging, multimedia conferencing, collaborative contact centers, and interactive multimedia response systems are provided through open application programming interfaces (API). Cisco CallManager provides basic call processing, signalling, and connection services to packet telephony devices.