What are the alternatives to Skype for business?

Question

Messengers

The task came from above - to find some simple solution for a local chat. It would seem that these chatiks are like dirt, of the most varied performance, choose - I don’t want to.
However, I completed the task for myself: I need a solution for corporate correspondence with the ability to install a server on a local network, with a desktop (browser is not suitable) windows client, mobile clients for as many platforms as possible (ideally - iOS, Android and Windows Phone / or at least Windows 10 Mobile). In correspondence, it is necessary to send the actual text itself and occasionally some files with documents. Audio and video calls are not required, but will be a nice bonus. It would also be a nice bonus to have some kind of global community of users with whom you can establish communication, or you can prohibit it and implement correspondence only among employees. Of course, it would be great if it was still free.
Only Skype for Business comes to mind, but, in my opinion, this solution is very cumbersome for us, my skill does not yet reach it, although at one time there was a one-time successful experience of raising Lync 2013. I know about Slack, but there is no server raise yourself. Jabber - do not offer, because you want some kind of solution that is developed and supported by specific people, and not just an open technology.
What's left?

Answer 1

hipchat

Answer 2

Google Hangouts

Answer 3

If you want a social network, take the Bitrix24 cloud. Clients for all devices, etc. There are boxes.