A versatile SIP server for handling VoIP calls, instant messaging, and presence services with robust scalability and security features.

Asterisk is a software that enables users to create and manage communication applications like voice calls, video conferencing, and messaging.

FreeSWITCH is a scalable communication platform that enables voice, video, and text across various devices and applications.

Routr is a versatile SIP server designed for modern communications, offering scalability, security, and seamless integration capabilities.

Kamailio is a robust, high-performance SIP server for handling thousands of call setups per second in telecommunication environments.