The external call transfer – is the call transfer to a telephone line other than the company’s telephone line. The internal call transfer – the transfer of an incoming call to another addressee registered on the same telephone line.
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.