Kamailio is described as '® (successor of former OpenSER and SER) 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); WebSocket support for' and is an app in the social & communications category. There are more than 10 alternatives to Kamailio for a variety of platforms, including Linux, Windows, Mac, BSD and Self-Hosted apps. The best Kamailio alternative is Asterisk, which is both free and Open Source. Other great apps like Kamailio are 3CX, FreeSWITCH, FreePBX and Yate - Yet Another Telephony Engine.