The PIMG is an eight-port stackable device that provides connectivy and integration between Unity and PBXs.It sits directly between them and emulate digital or analog phones lines to connect with the PBX and uses SIP to connect with Unity over the IP network. Because PIMG connects to the Unity server over an IP Network, it is no longer mandatory to install a voice card into the sever. Also PIMG and PBX can be connected through a IP WAN.
Each PIMG has 8 ports and we can stack up to 9 elements, so it gives us 72 simultaneous voice port connected to a single Unity server.