Kamailio
The Open Source SIP Server
Kamailio is an open source SIP server released under GPLv2+, written in C for Unix and Linux systems. It can operate as a SIP proxy, registrar, location server, application server, dispatcher, or WebSocket server, and is used to build VoIP and real-time communication platforms, scale SIP-to-PSTN gateways, and front media servers such as Asterisk, FreeSWITCH or SEMS. It runs on embedded systems as well as large multi-core servers.
The server uses a modular architecture with more than 150 modules in the source tree, covering SIP routing, load balancing, least cost routing, NAT traversal, failover, accounting, authentication and authorization. It supports UDP, TCP, TLS and SCTP transports, IPv4 and IPv6, WebSocket for WebRTC, SIMPLE presence and instant messaging with an embedded XCAP server and MSRP relay, and IMS extensions for VoLTE. Configuration is handled through a scripting language for the config file, with runtime updates. It connects to backends including MySQL, PostgreSQL, Oracle, RADIUS, LDAP, Redis, Cassandra, MongoDB and Memcached, and exposes control interfaces via XMLRPC and JSONRPC, plus SNMP monitoring. Programming interfaces are available for Perl, Java, Lua, JavaScript, C# and Python, along with CLI tools kamctl and sercmd and the Siremis web management interface.
Kamailio is intended for developers and operators building enterprise or carrier SIP services. It is distributed as free open source software under GPLv2+, with no paid editions or trials indicated.
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