It does not mean that when telecommunication core network has been building than they ready for service. Data Com network is needed to support many kinds of telecommunication services. The term of  Data Com network used to refer to the routing purpose, how the packet will be delivered from source address to destination address. Data Com network is needed in every telecommunication infrastructures; they responsible to connect equipments that locate at different place and area and find the best way the deliver the packet.
We can summarize the function on Data Com network on the telecommunication service such as mobile internet service are;

1. Routing the packet to the destination address

To ensure that packet was delivered to the right destination, Data Com Network implement routing protocol such as static routing, OSPF, BGP, eBGP

2. Finding the best way to deliver the packet

Usually the shortest path is to representing the best way to reach the destination address. Data Com network will find which is the fastest way to deliver the packet

3. Integrating the entire of telecommunication network infrastructures

By assigning an IP address to each network elements, the entire of telecommunication infrastructures can be accessed and monitored from the head quarter

4. Permitting and denying particular address to access particular network (security policy)

This is a mechanism to protect the network from huge illegal traffic

5. Preventing unauthorized traffic from public network to access to internal network

Data Com is running on the 3 of 7 OSI Model, they are physical, data link and routing layer. Meanwhile equipments which used to use to run Data Com function are Router, Switch/Catalyst, Cabling, Firewall. .Actually Data Com network is very urgent and critical to support telecommunication service such as mobile internet service . Any major problem to the Data Com network will impact to almost telecommunication service e.g. mobile internet service . Telecommunication core network are integrated one to each other by connecting through Data Com network. HLR, MSC, BSC, BTS, SMSC and others telecommunication core network will be interrupted when the core Data Com network has a problem and it means that Data Com network plays the key role to the telecommunication services. To ensure that their role is running well, many technology are applied on the Data Com network e.g. Multi Protocol Label Switching (MPLS), ATM and high level routing protocol