Can you recommend some good instant messaging suitable for enterprises?

Currently imo, rtx, oa, etc. The market evaluation is good and it is suitable for enterprises. Imo is a lifelong free instant communication. As long as there is an external network, you can communicate with the employees of the company on imo. Rtx and oa are charged, and servers need to be deployed. The cost of the server is relatively large, ranging from tens of thousands to millions. Their functions are similar, but oa pays more attention to the approval of the process, and sometimes urgent things have to be delayed. Another advantage of imo is that it can realize remote communication. As long as there is an external network, people in different places can fully grasp the company's dynamics. Our company uses imo, and the effect is very good.