What is it and how does CORE work?

In telecommunications, the Core Network is the central element of a network that offers services to customers who are connected by the access network. There are a number of services that the core network provides, but one of the main functions is to route phone calls through the PSTN (public switched telephone network). Today we will see in JSC Ingenium, provider of turnkey services and solutions for MNOs and MVNOs, what is Core and how it works.

What is Core?

A core network is the central part of a telecommunications network that offers numerous services to customers who are interconnected by the access network. Its key function is to direct phone calls over the public switched telephone network.

In general, this term means the highly functional communication facilities that interconnect the primary nodes. The core network provides routes to exchange information between various subnets. When it comes to enterprise networks serving a single organization, the term backbone is often used instead of core network, while when used with service providers, the term core network is predominant.

Therefore, it can be said that this term is also known as network core or backbone network.

How does core work?

The installations and devices that are used for core or backbone networks are typically routers and switches, although switches are used more frequently. The technologies used for the main installations are essentially data link layer and network technologies, including asynchronous transfer mode (ATM), IP, synchronous optical networks (SONET), and dense wavelength division multiplexing (DWDM). For backbone networks used by companies, in many cases a 10 Gb Ethernet or Gigabit Ethernet technology is also used.

Core networks typically offer the following features:

• Aggregation: the maximum degree of aggregation can be seen in a network of service providers. Next in the hierarchy within the central nodes are distribution networks, followed by edge networks.
• Authentication: determines whether the user requesting a service from a telecommunications network can complete the task within the network.
• Call or switch control: determines the future interval of a call based on the processing of call signaling.
• Load: deals with the processing and collection of the load of data created by multiple network nodes.
• Service invocation: A central network executes the service invocation task for its clients. The request for the service may occur online with some precise activity (such as call forwarding) by users or unconditionally (such as call waiting).
• Gateways: Must be used on the core network to access other networks. The functionality of gateways depends on the type of network to which they are connected.

What is a mobile core network?

One of the most critical parts of a mobile network is its core network which is sometimes also called a mobile core. Mobile networks are complex and consist of several key entities in their architecture. Depending on the network technology, e.g. GSM, UMTS, LTE, NR, etc., the architecture may be different. These network entities are grouped together to form several parts of the overall mobile network, including the radio network, core network, and transport network. The mobile network then connects to external networks, such as PSTN and the Internet, to communicate with the outside world. 

Before we get into the functional details, let’s first define the mobile core network to understand what it does and why it exists.

A mobile core network is a central part of the overall mobile network. Allows mobile subscribers to access services they are entitled to use, e.g. international calls. The mobile core network is responsible for critical functions such as subscriber profile information, subscriber location, authentication of services, and switching functions required for voice and data sessions.

With the evolution of mobile networks from 2G to 3G, 4G and 5G, the mobile core network has also evolved considerably. In the early days of digital mobile communications, the core network for 2G GSM was called the Network Switching System (NSS). NSS only supported circuit switching, which mainly allowed voice calls, SMS, and limited data services. 

Later, with GPRS (General Packet Radio Service), packet switching was introduced in the mobile core network to support efficient data services (mobile Internet). As a result, two nodes, SGSN (Serving GPRS Support Node) and GGSN (Gateway GPRS Support Node) became part of the 2G core network. 3G UMTS (Universal Mobile Telecommunication System) core networks followed the same approach for circuit and packet switching services. However, 4G LTE (Long Term Evolution) networks use a more advanced core network called Evolved Packet Core or EPC.