Core network typically providing the followings functionality
1.Aggregation : the highest level of aggregation in a service provider networks. The next level in the hierarchy under the core nodes is the distribution networks and then the edge networks. Customers premise Equipment ( CPE) do not normally connect to the core networks of a large service provide.
2. Authentication: The function to decide whether the user requesting a service from the telecom network is authorized to do so within this network or not.
3. Call Control Switching: Call control functionality decides the future course of call based on the call signaling processing. for e, g switching functionality may decide based on the called number that the call be routed towards a subscriber within this operator networks.
4.Charging: This functionality handles the collation and processing of charging data generated by various networks nodes. Two common types of charging mechanisms found in present day networks are prepaid charging and post-paid charging.
5.Service Invocation: Core network perform the task of service invocation for its subscribers. Service invocation may happen based on some explicit action(for e, g, call transfer) by user or implicitly ( call waiting). Its important to note however that service execution may or may not be a core network functionality as third party networks / nodes may take part in actual service execution.
6. Nateways: Gateways shall be present in the core network to access other networks gateway functionality is dependent on the type of network it interfaces with.
Physically one or more of these logical functionalities may simultaneously exist in a given core network node.