Telecom OSS/BSS Billing Systems Overview

Let me try and provide you a peek into the process of OSS/BSS softwares and their working methodology.

OSS/BSS software work at the Application layer and hence they work well for data as well as voice services. The software which provides OSS/BSS services for all these different kinds of services is said to be providing a convergent billing solution.

Convergent Billing Solutions can be applied for both Prepaid and Postpaid Billing systems. The diagram and article below focuses on the generic Billing flow.

The network layer consists of devices like Access Servers, Universal Mobile Telecommunications System (UMTS), Gateway GPRS Support Node (GGSN), Cisco Netflow Collector and such devices which help the End User connect with the Network Layer and hence the OSS/BSS.

AAA server

The network devices like a RAS - Remote Access Server, VPN server, Switch with port based application or a Captive portal and NAS/BRAS - Network/Broadband Access Server are connected to the AAA server, usually a Radius/Diameter server which handles the tasks of Authentication, Authorization and Accounting. A Diameter server is the upgraded version of the RADIUS server. The RADIUS/Diameter server checks if the information is correct using authentication protocols like PAP, CHAP or EAP. Modern RADIUS/Diameter servers can directly access databases for authentication.

The AAA server usually returns one of three responses to the NAS/BRAS:

Access Reject : Reject Login

Access Challenge : Challenge Login for more info

Access Accept : Accept Login

Provisioning

The provisioning server is primarily responsible for managing access rights and privileges in conjunction with the AAA server. A provisioning server helps the AAA make decisions about providing different access rights to the users.

Mediation Engine

A mediation engine helps in refining and converting the incoming CDRs from the provisioning server into information that can be accessed and used by the Rating/Charging module of the system. A mediation engine is required as an interface between the AAA server and the Rating and Charging systems when the Rating and Charging system cannot understand the CDRs generated by AAA.

The connection between the Network Layer and the Mediation Layer is through the SOAP protocol over HTTP/XML, SNMP or FTP/FTAM. The data transfer can occur real time - for Prepaid Billing, Batch mode through Push or Pull techniques.

Rating and Charging

The Rating and Charging module applies different rating rules to the processed CDRs it receives from the Mediation layer. After the rates are applied, it updates customer account according to the rates, creates a billable data record and sends the same information with the promotion information to the Billing layer. The Rating and Charging Layer is closely connected with customer management. Customer management is primarily for the back office to be able to define new rates, rating mechanisms and apply charges.

Billing and Bill generation

The Billing layer generates bills based on the Billing Data Records it receives from the Rating and Charging Layer and then it applies taxes, discounts, calculates charges and finally generates invoice records for every customer. The Billing Layer will also interface with various other modules like the web self care module, Order Management module. Payment module, Pre and Post Paid integration and the Partner Management module. The Billing Layer can also be used as a standalone Interconnect Billing Solution provided it gets all the requisite details from the Interconnect partner.

The Billing System will interface with the Customer Relationship Management layer, Web Self Care layer and the Reports Layer.

This article tries to provide a very brief overview of how OSS/BSS Billing systems work. Most of the modules described here are not according to the standards set by the TMForum, but help best to understand how the process occurs. To know more about TMForum initiatives and standards, Watch This Space.