Kamailio

Kamailio is an open-source SIP signaling server that implements the Session Initiation Protocol as specified by the IETF in RFC3261. It functions as a server-side application designed to handle the signaling required for Voice over IP (VoIP), instant messaging, and presence services. The software acts as the control plane for communication, managing how calls and messages are initiated, routed, and terminated across a network.

The software is deployed on servers to manage communication flows for a wide range of scales. It is specifically designed for high scalability, making it suitable for IP telephony operators and carriers that manage a large subscriber base or route a significant volume of calls. Beyond carrier grade use, it is also used in enterprise environments or for personal needs to establish private communication infrastructure.

Key features

• Implementation of the IETF SIP open standard protocol
• Support for large scale VoIP deployments
• Routing for high volumes of calls
• Management of instant messaging services
• Presence service functionality
• Modular architecture for extended feature sets
• Integration with IP telephony carrier infrastructure
• Support for various Linux package formats including deb and rpm

Kamailio is developed and managed by a global community. The project has a long history, starting in 2001 as the SIP Express Router (SER) at the Fraunhofer Fokus research institute. Following a period of divergence with a fork called OpenSER, the two projects merged to form the current Kamailio project. This collaborative development model ensures the software remains flexible and secure while adapting to modern communication needs.

Administrators can install the software from source code or via official repositories. The project maintains extensive documentation, including a wiki and module specific guides, to assist with the configuration of complex routing logic and security parameters. It is primarily intended for network engineers and system administrators building communication platforms.

This software serves as a core infrastructure component for organizations requiring a scalable signaling layer for real time communication platforms.