Diameter Protocol and Its Role in the Success of Online Charging System

As telecom operations become increasingly complex, the demand for reliable charging solutions has risen. Telecom operators are trying hard to find charging solutions that can make their tasks simple. In the current situation, Online Charging System (OCS) has come across as a trustworthy system that most telcos have put their faith in. OCS is a specialized tool that is used by a telecom service provider to charge a user for services in real-time. It handles charging transaction control and correlation along with subscribers’ account balance.

OCS: Real Time Charging Solution

For prepaid customers, real time charging is needed for accurate and effective billing. As OCS allows for charging in real time, it has become the go-to tool for many telcos. An OCS can charge transactions in two different ways:

1.     Event Based Charging

This type of charging is carried out by an event based charging function (EBCF). It is utilized for charging events depending upon their occurrence and not their duration or volume. Some examples of event based charging are SMS and mobile data.

2.     Session Based Charging

Network or user sessions are charged by what is known as session based charging function (SBCF). Some examples are voice calls, IP CAN bearers, IP CAN session or IMS sessions.

Diameter Charging for Real-Time Credit Control

Along with charging, credit control also plays a vital role in telecom transactions. It is based on diameter charging protocol, which is utilized for exchanging AAA (Authentication, Authorization and Accounting) information in 4G and IP Multimedia Systems (IMS) networks. It is an improvement on the older RADIUS (Remote Authentication Dial-In User Service) and LDAP (Lightweight Directory Access Protocol) AAA protocols. 

The Connection between Diameter Protocol and SIP

In an IMS network, SIP (Session Initiation Protocol) and Diameter Protocol play an important role. On one hand, SIP controls IP sessions that take place in real time and on the other hand Diameter protocol authorizes, authenticate and provides precise billing information. Without this relationship between SIP and Diameter protocol, it would be difficult for online charging system to carry out its operations.

Some of the advantages offered by Diameter protocol are listed below:

3.      Comes with in-built failover mechanisms that ensure 100% message delivery

4.      Offers secure transmission of AAA messages by utilizing TLS or IPSec

5.      Provides peer-to-peer architecture that offers improved flexibility

6.      Trustworthy transmission of AAA messages over SCTP or TCP

Summary

Diameter protocol is an improvement over RADIUS and forms an integral part of an online charging system. It supports attributes like quality of service, bandwidth allocation, policy control, dynamic rules along with charging mechanisms that are required for modern-day telecommunication operations.

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