The call manager is a powerful call-processing component of Cisco Unified Communications solution.
The call manager is a call processing component of CUCM. It provides voice, video, mobility and presence services for businesses with up to 60,000 users. It is scalable, distributable and highly available enterprise-class IP telephony call-processing system. It creates the workspace that contains the enterprise telephony features to packet telephony network devices such as IP phones, mobile devices, etc.