It is a device capturing and controling all the signals, which are being created by the whole system, especially the made and received phone call signals. The device is mostly used for connecting regular phone system with the Internet and backwards.
Call center - is a center where the company's incoming and outgoing calls are taken care of, it can be a centralized office, used for receiving and forwarding high volumes of information, incoming by the way of phone calls. There are two types of call centers internal call center and outsourced call center.