Customers almost always have either prepaid or postpaid accounts with their operator. Postpaid accounts capture usage information from the network in the form of billing records, or call detail records (CDRs). One or more CDRs may be generated for each telephone call or service used.
These are streamed or batch processed into large data processing centres which “rate” (ie work out the price) for each service delivered. Often a regular (eg monthly) bill is produced, which handles more complex features such as recurring charges, volume discounts and other special cases. Once the postpaid bill is produced, this is passed across to the charging and settlement systems which collect the money for the bill, either as a direct debit from the customers bank account or other payment mechanism.
The collections system tracks that bills are being paid and takes corrective action when this is not the case. This process is quite secure as long as the devices which generate the billing records (CDRs) are under the control of the operator, and their can be no doubt that the service is being used by the genuine customer. The operator performs credit checks to limit the risk of unpaid bills, but would expect to write-off some unpaid debts. Prepaid accounts authorise each transaction before it takes place.
This requires “real-time” systems directly connected to the network which are queried before each call, text or data service is used. The prepaid system must “rate” (i.e. calculate the price) for each call and check and reserve the account balance before authorising it to proceed. Whilst this is more complex and demanding to implement than postpaid billing, it avoids the risk of unpaid bills and significant improves the cashflow for the operator because payment is made in advance. It is also secure, as long as devices which query the prepaid system are all under the control of the operator, and their can be no doubt that the service is being used by the genuine customer. However, this method is considered less appropriate for corporate and high spending customers, who might otherwise limit their spending.