Text messaging within the network (without using the Internet)?

Question

Computer networks

Greetings.
Tell me a convenient program for correspondence over the network.
She needs:

1. convenient simple interface
   
2. convenient contact list, highly desirable with groups (the ability to send one message to a group of users)
   
3. a list of contacts that can be easily (as a file, for example) transferred from a computer
   
4. work without access to the Internet
   

General chats, in principle, are not needed, only 1 on 1
Maybe someone faced a similar task? Share your experience. Thanks

Answer 1

Depends on what kind of software you are already using. In the general case - jabber. If the mail is spinning on the exchange, then Lync seems to be the best solution

Answer 2

In general, with a server, Jabber will be the universal answer.

Answer 3

LanSend

Answer 4

man talkd

Answer 5

net speakerphone

Answer 6

Big Ant

Answer 7

The description of the problem is complete and understandable.
It is not clear what platforms customers are sitting on.

Answer 8

Jabber is the most versatile option. And I do mailing messages based on the antivirus admin panel. One-way is very convenient.