If you had elaborated on the type of industry you are in, the location, the number of employees, and the specific problem with communications (e.g., if you have a policy of encouraging people to speak in English and people are more comfortable with their mother tongue), perhaps we could provide tailored solutions.
However, for starters, I would suggest the following:
- Make induction compulsory, and at each induction, have a policy that a different person from the functional departments will introduce the functional team and allied details to the new joiners.
- Encourage the departmental heads to interact more with the new joiners and ensure that the new joiners are given assignments that will require them to meet other departmental personnel and interact with them.
- Implement some employee engagement activities that are monitored to ensure that no specific group hogs the center stage, but everyone gets a fair chance to participate.
- You might also encourage activities like a weekly book review or a weekly review of movies/economic news, which will be allocated in turn to employees. Feedback on their contributions must be given so that they receive both encouragement and learning points.
Best Wishes