At Zaleos we have a strong background on Real Time protocols such as SIP or WebRTC. One of the Open Source products that we use most is called Kamailio [http://kamailio.org], which is an Open Source SIP Server that is able to handle thousands of VoIP calls [https://en.

As a company developing VoIP software, we need a solid developing and testing SIP [https://www.ietf.org/rfc/rfc3261.txt] ecosystem. SIP (Session Initiation Protocol) is a signaling protocol used for initiating, maintaining, modifying and terminating real-time sessions that involve video, voice, messaging and other communications applications and services

SSH'ing [https://en.wikipedia.org/wiki/Secure_Shell] into several VMs in a daily basics can be challenging and error-prone. In most cases you have to remember a bunch of different options: ips/domains, users, ports, ciphers… It’s hard to be updated when servers are added/removed