Do you need a corporate free portal with chat, mail, shared folders to facilitate interaction between employees of government agencies and branches?

Question

Data storage

There are several structures at the municipal level.
Interaction within the structure is of a telephone-chat nature. Interorganizational telephone, very rarely email. mail. (mostly from top to bottom).
In addition, the throughput channels of individual branches are limited to 10Mbps.
In the local networks of organizations, most often the interaction is based on the working groups of Windows XP and 7ki.
I would like to make a decentralized solution based on open technologies in order to:

• Employees could share documents within and between organizations. At the same time, it is important to be able to work with documents in the absence of the Internet. Perhaps the versions of the documents would be useful, since joint work is supposed. And searching for a document.
  
• Exchange letters and receive messages from external mailboxes.
  
• Conduct real-time communication, such as a chat, or a voice conference.
  
• Have calendars with the ability to set tasks from managers to subordinates.
  

Prompt what tools and means to choose for the decision of similar tasks. Given the lack of a target budget. And the number of employees is 20 - 50 people.

Answer 1

можно попробывать Alfresco, но так как она бесплатна, настраивать будет тяжко. Вроде есть еще похожая система odoo, но опять же настраивать самому придется.
Скорее всего со временем или сразу появиться необходимость в регистрации входящей корреспонденции, назначать ответсвенных, сроки, далее согласоввывать документы через эту систему.

Answer 2

"corporate free" - either shit, or it will take over 9000 hours to customize

Answer 3

Given the lack of a target budget.

In 2015, officials had microbudgets and kickbacks, in 2016 they want it for free, in 2017, apparently, you will be required to pay for the fact that you will work for free for the good of your homeland.
Everything is free separately and not everything is available locally: chats separately, task management separately, versioned system + shell, and so on.