Charging Procedure in GSM Network

Charging Procedure in GSM Network: In the fixed network system, the used network cost charging is normally determined by collecting metering pulses, by which the exchange can calculate the price of the call. This method is called time charging. The calling subscriber/customer is normally the one who pays for the call. In the mobile network the called subscriber is normally also charged for the so called roaming leg, because caller does not necessarily know, where the second user is located. But now roaming is free for the all mobile users.Telecom operators charge the cost in another ways.

Charging in GSM networks are also similar principles to that used in fixed telephone networks. In addition to a standard fee, subscribers/users have to pay for the calls they make and the services they use. However, there are a few differences in how the costs are calculated and who is liable to pay them.Now I would like explain in details.

GSM Network Charging 

Charging Procedure in GSM Network

GSM Network Subscription Charge 

When a person joins a GSM network, customers/users receives a personal SIM card from the telecom network operator and his basic information is recorded in the network databases such as the HLR. To cover the costs of these operations, network operators often charge the subscriber/customers an initial subscription charge.

After the subscription has been made and the subscriber has become a valuable customer of the particular telecom network, he is usually charged for the availability of the network services and the right to use their network. This is a regular fee which is charged irrespective of whether the subscriber makes any calls or not. This type of charge from telecom operators is also known as renting the service of the network.

There are three different way of charging from the customers.Installation (SIM) fee, Renting of the service and Use of the network.

Charge for use of the GSM network

The third charging type is applied for the use of available network on a call by call basis. There are many factors that affect how the subscriber/customer is charged for making a call. The below mentioned list of parameters that can be used as a basis for charging the subscribers.
➤Type of the service, e.g. speech, short message service.

➤Duration of the call.

➤Time of day the call was made, e.g. working hours, evening.

➤Destination of the call.

➤Origin of the call, e.g., a certain cell.

➤Use of networks, e.g. the PSTN.

➤Use of supplementary services such as call forwarding and call barring.

➤Use of radio resources.

➤International Roaming leg (explained later).

Whom to Charge

Suppose that a number dialed by the calling subscriber.The dialed number includes the national destination code, which identifies the called subscriber’s local network.If the called subscriber is registered in a location area belonging to his home network, the connection is established.

If however, the called subscriber is outside the service area of his local network (in a foreign country, for instance) and is connected to another telecom GSM network, then the call has to be routed to him using the services of one or more foreign networks.

In such a case, we have to know about international roaming leg, which refers to the connection between the home network and subscriber via a foreign network. In such a case, the charge for the all will be shared according to the following principle:
➤The calling subscriber pays for the connection to the number he dialed (MSISDN).

➤The called subscriber pays for the international roaming leg.

The same principle is applied when the mobile subscriber has forwarded incoming calls to another number. The calling subscriber is only responsible for the costs incurred by calling to the mobile station, and the mobile user pays for the forwarded call.

This may seem strange and complicated, but the reason is quite clear, the calling subscriber

does not necessarily know the location of the called subscriber or the services and connections that are required to access him. The calling subscriber only knows that he is dialing a number in a certain mobile network, and therefore he can only be charged for the services that he is aware of.

The called subscriber knows, at least he should know, whether he is using the services of a foreign network or some chargeable supplementary services of his home network, and therefore he is liable to pay for them.

Collect call is the third case in which the called subscriber pays for the call. A collect call in a GSM network is similar to a collect call in a fixed network: first the called subscriber has to accept the call, after which he is responsible for all the costs.

Charging Procedure in GSM

In the GSM network there are so many different ways to define the charging that it is sensible to create a record in the MSC or/and HLR about every event which can be a basis for charging. These events can be the defined call cases or other possible chargeable eve nts, such as location updates. The record containing the information about one chargeable event is called the charging record.

These records are stored primarily as charging files in the MSC or HLR and then transferred to a separate billing centre. The serving operator controls the entire charging process. The process begins when a call is set up and at the same time, a charging record is opened in the serving MSC/VLR. In general the first and the last MSC involved in a call set up, collect the charging record.

Charging Record in GSM Network

GMSC is responsible for creating charging records

As the call continues, the subscriber moves in the service area of the operator and enters the service area of another MSC/VLR and thus an inter-MSC handover is performed. The charging record is not transferred to the new MSC during the handover. Instead, the first MSC keeps record of the call as long as it lasts.

When the call has been released, the charging record is closed. When a sufficient number of charging records have been accumulated they are sent to a billing center in one bulk via Ethernet connection.

Billing Center 

Transfer of charging data to Billing Center

As the actual charging is affected by a variety of factors, the charging record contains all the events that can be used as a basis for determining the charge.Information for one customer is collected from many MSCs and billing center that the mobile has visited and is presented as one bill.

Distributed GSM Network Charging

In order to produce bills for each subscriber, Billing Centers should collect detailed charging data from all the MSCs within the PLMN.With International Roaming, this operation should be extended covering all the PLMNs where a Roaming Contract is signed. Charging information must be collected from the Billing Centers (BC) of all the networks that subscribers have been visited and passed to the Billing Centers of the home network.

When two GSM telecom operators sign a “roaming contract”, they agree how often they will transfer charging data between each other. The home billing center analyses the charging information collected from all the networks where a roaming contract exists, and produces a bill for each customer.