Comunications Manager Express (formerly know as CallManager Express or CCME) is a fully-featured VoIP PBX, and is Cisco's offer for small to medium PBXs and key systems.

• Comunications Manager Express is implemented as a set of services that run on Cisco router platforms, concurrently with the data IOS features.
• Configuration data is kept in router configuration file.
• The administration interface is implemented mainly with command line. There an HTML/Jscript utility providing basic administration features, and an user interface on a per-user basis.
• Comunications Manager Express supports redundancy, with a secondary router of same or different capabilities

Here are some links to more information:

• Quick guide to CallManager Express configuration

• Integrate with Asterisk|How to integrate Cisco CallManager and Asterisk

• Cisco Call Manager consultants

• Cisco Call Manager Express consultants

• Cisco CallManager Express - voicepulse