This is a process of connection between a computer and an ordinary phone. For example, one can call from Skype to a cell phone by dialing a specific number.
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.