Billing - process of making and sending bills to customer for services and goods.
Billing system - software applications and data bases for billing processes. In telecommunications billing system functions also include service data collecting, payment collecting, charging, balance manegement, credit control, service provisioning, customers relation management etc.
Convergent billing system (telecommunications) - billing system that enables common management of different networks, service types, traffic classes as well as different balance management methods.The convergence of balance management methods includes prepaid and postpaid. The convergence of service types includes telephony, messaging, data transfer, content access etc.The convergence of networks includes fixed, mobile, satelite networks etc.