You need to set up an IP phone for each user and connect it to the Internet, then configure it to connect to the server. To configure the phone, you will need to know the Device ID (called username in some phone configurations), password, and server address.
To find IP phone setup instructions, go to CONTROL PANEL > Users and click on the display name of the user. Go to the Hosted PBX tab, click Device Setup Intructions, and select the type of phone you are using to view personalized instructions for that phone.
Here you can select the user and the phone device:
You may additionally configure wireless phones or devices. Read the Knowledge Base article How do I set up a cell phone or wireless device? for more information.
Important note: The Device ID and password can only be used for one phone's configuration. If you use the same settings to set up a second phone device, this will result in dropped calls. If you want to set up several phone devices, you must add additional phone devices in the user settings to generate additional sets of configuration settings.