Primary Function

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.