A core network is a telecommunication network's core part, which offers numerous services to the customers who are interconnected by the access network. Its key function is to direct telephone calls over the public-switched telephone network.
In general, this term signifies the highly functional communication facilities that interconnect primary nodes. The core network delivers routes to exchange information among various sub-networks. When it comes to enterprise networks that serve a single organization, the term backbone is often used instead of core network, whereas when used with service providers the term core network is prominent.