This is a simplistic description of the operation of a customer care and billing
system within a telecommunications operator.
The diagram illustrates the key components of the system. The billing system is one
or more software packages residing on a computer system. This is accessed from computer
terminals connected to the computer.
The telephone exchange or switch is connected to the billing system via an interface,
which is sometimes referred to as mediation.
At its most basic, the telephone exchange or switch generates a piece of data representing
each telephone call, which is passed through the mediation interface into the billing
system. This will generate a bill line on the customer’s statement representing the
call and the cost of the call.
The billing system will be closely associated with an invoicing system and will have
information regarding outstanding invoices and invoices which have been paid.
Of course there is much greater complexity.
Information from the Telephone Exchange (Switch)
Pieces of information sent from the exchange to the billing system are often referred
to as Call Detail Records. It is rare that one telephone call results in one call
Rather the switch might indicate the beginning of the call, the end of the call precipitating
another information burst. It will be up to the mediation or billing system to interpret
the data correctly.
In the case of a mobile telephone operator call detail records might be generated
every time that the user roams between base stations, or at regular intervals during
More sophisticated network services will also generate call detail records. For example
redirected calls, conference calls, access to special services such as telephone
A progressively increasing number of mobile services will require billing. Text messages,
picture and video messages, access to the Internet etc.
The above discussion illustrates the likely complexity of information being sent
from the telephone exchange towards the billing system.
Mediation can be used to pre-process the information, reducing the load on the billing
system itself, also providing a buffer to store information during times of peak
Let me introduce another concept. Up to this point the telephone exchange has sent
information to the billing system. There is potential for information flow in the
reverse direction. For example activating and deactivating lines – due to new customers,
ceasing or non paying customers.
In addition a message can be sent to the switch to turn on or off a service such
as call redirection.
So the Mediation Device may facilitate communication in both directions – out of
and in to the exchange.
The Billing System
In reality a billing system incorporates an account management system for generating
invoices, statements, and receiving payments.
It is also likely to incorporate a Customer Care System to support the customer facing
staff of the telecommunications operator.
Staff in offices, shops or in call centres will be able to manage a customer’s account
from a computer terminal connected to the billing system.
They will be able to set up an account and terminate it. Give information to the
customer concerning outstanding balance, accept payment – eg via credit card. Activate
new services. And many more functions.
Going back to the beginning, it is clear that the billing system takes records from
the telephone exchange and raises charges. This process is called rating. A telephone
call is ‘rated’ to give its cost – usually dependant on the dialled number and the
duration of the call.
Again this is simplistic. Rates may vary between customers. Customers who have set
up a friends and family list – or a calling circle will get a special discount when
calling those numbers. Corporate users might be given a discount dependant on overall
So, in reality, calls will often be rated and then re-rated.
Fixed and Periodic Charges
Most customers will have fixed or periodic charges for telephone rental, line rental,
particular services such as an exchange based messaging service.
Each customer will be placed on a bill cycle such that each month or quarter, the
billing system collects together all the relevant information for that customer,
and generates an invoice.
This might be sent through the post or sent by electronic mail, or posted on the
Large billing systems will have many bill cycles each month, say 20, the remaining
days being used to generate management information and back up and archive data.
The Devil is in the Detail
This very very simplistic description of a telephone billing system will provide
the reader with a small insight into the complexity of the real thing.
As with many complex systems the devil is in the detail. Making it all work correctly!
At 10.00 on a Monday morning a telephone system will typically be connecting millions
of calls. The correct rating and billing of those calls is the requirement of the