Cisco Call Manager is the software-based call-processing component of the Cisco IP telephony solution, part of Cisco AVVID (Architecture for Voice, Video & Integrated Data). The software extends enterprise telephony features & functions to packet telephony network devices such as IP phones, media processing devices, voice-over-IP (Vo IP) gateways, & multimedia applications. Additional data, voice, & video services such as unified messaging, multimedia conferencing, collaborative contact centers, & interactive multimedia response systems interact with the IP telephony solution through Cisco Call Managers open telephony application programming interface (API).