Kamailio (OpenSER) 3.0.0 release represents a big step forward for the SIP server, with many new features and enhancements. Along with ability to run SIP Express Router (SER) modules due to the new SIP-Router.org core framework, it brings asynchronous TCP, refurbished secure transport TLS and SCTP, new command line interface (cli), number portability and topology hiding support, memcached connector and internal dns caching system. The presentation will focus to highlight what Kamailio 3.0.0 can offer to build scalable VoIP platforms. Kamailio (former OpenSER) is an Open Source SIP Server released under GPL, able to handle thousands of call setups per second. Among features: asynchronous TCP, UDP and SCTP, secure communication via TLS for VoIP (voice, video), SIMPLE instant messaging and presence, ENUM, least cost routing, load balancing, routing fail-over, accounting, authentication and authorization against MySQL, Postgres, Oracle, Radius, LDAP, XMLRPC control interface, SNMP monitoring. It can be used to build large VoIP servicing platforms or to scale up SIP-to-PSTN gateways, PBX systems or media servers like Asterisk, FreeSWITCH or SEMS.