A method for determining a capacity of a virtual machine in a VoIP system includes determining a resource configuration of the virtual machine including a number of CPU cores, a CPU clock rate, or a memory size. The virtual machine may be configured as a trunk, conference bridge, phone switch, session border controller, router, or another device in the VoIP system. The method also includes sending the resource configuration from the virtual machine to a VoIP system configuration application. The VoIP system configuration application may be an application running on the virtual machine or an application running on a server separate from the virtual machine. At the VoIP system configuration application, a capacity of the virtual machine is determined based on the resource configuration. The capacity may determine a number and type of telephony features supported by the telephony device in the VoIP system.