1. Installing VNC server software: First, you need to install VNC server software on the communication server, such as TightVNC, RealVNC or UltraVNC. These softwares usually have free versions. You can download it from official website and install it according to the instructions.

2. Configure VNC server: After installation, you need to configure VNC server to enable remote control function. Configuration includes setting access password, selecting port number, etc. For specific configuration methods, please refer to the official documents or online tutorials of VNC server software.

3. Configure the firewall and router: If the Unified Messaging server is located in the internal network, you need to ensure that the firewall and router settings allow VNC connection. You need to open the VNC port on the server (default is 5900) and set up port forwarding on the router to forward external network requests to the VNC port on the server.

4. Install VNC client: Before remotely controlling the Unified Communications Server, you need to install VNC client software on the local computer. Similarly, you can choose TightVNC, RealVNC or UltraVNC. According to your personal preference.

5. Connect to the Unified Messaging server: Open the VNC client and enter the IP address and port number of the Unified Messaging server, as well as the access password set on the server. After the connection is successful, you can remotely control the communication server through VNC client.

Please note that the specific operation steps may be different due to the different model and operating system version of the Unified Communications Server. Before installation and configuration, it is recommended that you consult the official documentation of the communication server or consult the technical support of the product for more accurate and detailed guidance.