Is it possible to limit communications between departments in skype for business?

Question

System administration

Good afternoon!
Faced such a situation. There is a parent company and several subsidiaries. Inside the daughters, communication occurs without problems, instant messages and video calls work. There is no such connection between the daughters. Only through the appointment of the meeting. Specialists from one daughter say that the problem is that there is no direct network interaction between the daughters. In the second daughter consider the possibility of interaction at the level of exchange servers is disconnected. That's actually the question. Is it possible to limit interactions between departments at the level of the Exchange server (Skype)?
Thank you.

Answer 1

The very posing of the question does not imply an answer to it.
There is no connection scheme (judging by the description, there is no common internal network and, as a result, these are just separate companies with their own separate infrastructure).
A common internal network is not needed for this case, it is enough to configure the federation on the edge. Exchange has nothing to do with it and it seems that either you do not understand what you are asking about, or the admins in both branches do not understand how it is configured.