Kamailio is an Open Source SIP Server released under GPL, able to handle thousands of call setups per second. Kamailio can be used to build large platforms for VoIP and realtime communications Ð presence, WebRTC, Instant messaging and other applications. It can also easily be applied to scaling up SIP-to-PSTN gateways, PBX systems or media servers like Asterisk, FreeSWITCH or SEMS.
Skype for Business offers features including presence, IM, voice and video calls, online meetings, conferencing, and telephony solutions that support enterprise-level collaboration requirements. Skype for Business Record meetings, share your screen, and annotate PowerPoint for real-time collaboration with up to 250 people and use whiteboard, polls, Q&A, and built-in IM during your business meetings to make them more productive. Skype for Business provides new client experience, Skype for Business Server provides several new features to improve manageability of on-premises servers and hybrid solutions. Skype for Business also supports the Lync client experience so that you can choose a phased upgrade approach to the new client experience for users. Skype for Business is also an integral part of Microsoft Office 365, providing PSTN Conferencing, Cloud PBX, PSTN Calling, and Skype Meeting Broadcast capabilities to Office 365 users.
