Cisco Unified Communications Manager (CUCM), also commonly refered to as Cisco Unified CallManager (CUCM) and Cisco CallManager (CCM), is a software based IP call agent platform sold by Cisco Systems.
CallManager is the call-processing component of the Cisco Unified Communications System. Cisco Unified CallManager extends enterprise telephony features and capabilities to packet telephony network devices such as IP phones, media processing devices, voice-over-IP ( VoIP ) gateways, and multimedia applications. Additional services such as unified messaging, multimedia conferencing, collaborative contact centers, and interactive multimedia response systems interact with the IP telephony solution through Cisco Unified CallManager APIs. Cisco Unified CallManager is installed on Cisco Media Convergence Server ( MCS ) 7800 Series of server platforms and selected third-party servers. It has a suite of integrated voice applications and utilities, including the Cisco Unified CallManager Attendant Console—an ad-hoc conferencing application, the Cisco Unified CallManager Bulk Administration Tool (BAT), the Cisco Unified CallManager CDR (Call Detail Record) Analysis and Reporting tool, the Cisco Unified CallManager Real-Time Monitoring Tool ( RTMT ), the Cisco Unified CallManager Auto-Attendant (CM-AA)the Tool for Auto-Registered Phone Support ( TAPS ), and the Cisco Unified CallManager Assistant application.
• 1994 Multimedia Manager 1.0
The product started its life as Multimedia Manager 1.0. The Multimedia Manager product was designed to be the signaling controller for a point-to-point video solution. It was originally developed for a HP-UX platform, but was later converted to the Windows NT 3.51 platform.
• 1997 Selsius-CallManager 1.0
Multimeda Manager 1.0 was renamed Selsius-CallManager (version 1.0) and changed from a video conferencing solution to a system designed to route voice calls over a IP network. It was during this time that support for the Skinny Client Control Protocol (SCCP) and Skinny Gateway Control Protocol (SGCP) were added.
• 1998 Selsius-CallManager 2.0
Selsius-CallManager 2.0 has been released and Selsius Systems was acquired later that year by Cisco Systems, Inc.
• 2000 Cisco CallManager 3.0
Selsius-CallManager 2.0 underwent a large design and engineering effort to enable scalability and redundancy to the software. Clustering was introduced at this time and [MGCP] support was added. The product was released as Cisco CallManager 3.0. There were a wide array of new features for this release that can be referenced in the Cisco CallManager 3.0 Release Notes document.
• 2001 Cisco CallManager 3.1
Product version and revision changes are introduced. This revision supported more gateway devices, IP phone devices and added more enhancements and features. Music on hold (MOH), support for digital interfaces on [MGCP] gateways, added support for XML and HTML applications in Cisco IP Phones, Extension Mobility (EM), call preservation between IP phones and MGCP gateways and Telephony Application Programming Interface (TAPI) is introduced.
• 2002 Cisco CallManager 3.3
Building from the previous 3.3 release, in  Cisco added even more enhancements to version 3.3. In addition to the various bug fixes found in most product releases additional support for QSIG was added. IP Manager / Assistant [IPMA] was introduced as well as configurable call waiting tones and scalability to 30,000 phones per cluster. Improved H.323 features and support which included multiple H.323 gatekeepers.
• 2004 Cisco CallManager 4.0
Cisco made a large scale release with CallManager 4.0. Included in this release were numerous new features. Previously IP phones were restricted to only 2 calls per any given line appearance. This caveat was eliminated and IP phones could now have a user configurable maximum (up to 200) number of calls per line appearance. Other features and enhancements of note added during this release were, Hunt group, Malicious call identification, Immediate diversion, Privacy for shared lines and Call barge.
Improved security with media encryption between phones, Multi Level Administration (MLA) allowed delegated administration and Direct transfer allowed a user to select two calls from the same line and connect them together. Call join allowed users to select several calls from a line and conference them together.
Later in the same year Cisco released a minor platform revision as CallManager 4.1. This version focused on improved stability and support for even more features. Several utility tools were added as well. Additionally, some of the new features of CCM 4.0 include greatly enhanced conference calling features, enhanced Client Matter Code (CMC) and Forced Account Code (FAC), Multilevel Precedence and Preemption (MLPP) and Malicious Call Identification (MCID). The Dialed number analyzer (DNA) was also introduced which allowed administrators to analyze how dialed strings route calls. CallManager 4.1 also enhances the encryption capabilities first introduced in CallManager 4.0. Additional security enhancements when using Cisco Phones 7940/7960/7970 or 7971 it is now possible to encrypt signaling as well as voice traffic itself.
CallManager 4.2 was released in parallel with CallManager 5.0 on Monday the 6th of March . At the same time Cisco re-branded the product "Cisco Unified CallManager" (CUCM); Cisco also added the Unified tag to all of their Voice and Video offerings (i.e. Cisco Unified Contact Center, Cisco Unified MeetingPlace). Cisco Unified CallManager 4.2 runs on Windows 2000 and includes new PABX features over 4.1(3) such as logging into hunt groups and call-forward on no coverage. CallManager 5.0 an applicance based Linix solution includes SIP end point support a feature not available on CallManager 4.2
Cisco renamed the product to Unified Communications Manager. Version 6 will merge all features of the Linux appliance (SIP support and licensing requirements) between the Linux platform and Windows version. The released version of Unified Communications Manager currently does not support the Windows platform.
• Support for multiple levels of server redundancy and survivability
• Choice of operating system environments (versions 4/5/6): Windows or Linux implementation
• Supports up to 30,000 lines per server cluster
• Supports a full range of communications features and applications
• Supports for a broad range of phone equipment and accessories to suit varying user requirements
• Supports a broad range of non cisco manufactured phone equipment