Kamailio®, the successor to former OpenSER and SE, is an open-source SIP Server released under GPLv2+. It can handle thousands of call setups per seconds. Kamailio is a platform for VoIP, real-time communications and instant messaging. It can also be used to scale up SIP-to PBX gateways, PBX system, or media servers such as Asterisk™, FREESWITCH™, and SEMS. Among its many powerful features are asynchronous TCP and UDP, secure communication via VoIP (voice, text, and video); WebSocket support WebRTC; IPv4 or IPv6; simple instant messaging with embedded XCAP servers and MSRP relay; asynchronous operation; IMS extensions to VoLTE; ENUM, DID and least-cost routing; load balancing and routing failover; accounting, authentication, and authorization; support for many backend system such as MySQL, Postgres and Oracle, Redis, Cassandra and Memcached, Redis, Redis, Redis, Redis, Redis, Redis, Redis, Redis, Redis, Redis, Redisk, MongoDB and MongoDB, Redis, Redis, Redis, Redis, Redis, Redis, Redis, Redis, Redis, Redist, Redis, Redis, Redis, Casandra, Casandra, Redis, Casandra, MongoDB and Memcached, MongoDB, MongoDB, MongoDB, MongoDB, MongoDB, MongoDB, Casandra, MongoDB and Memcached, Casandra, MongoDB and Memcached