AsteriskBilling.com - General technical and billing information for VoIP operators using Asterisk PBX.
PIN based prepaid billing allows the user to call a pre-defined number (local or toll-free) and enter their pin (calling card) number to authenticate the call. Their balance is calculated prior to placing the call and the call is dropped when the balance reaches zero.
A good Asterisk billing application will handle both the initial orders and refills in realtime, as well as send automated e-mails alerting of their pin numbers, low balances, etc. The Asterisk billing application's user area should display the CDR for the user to review in realtime. On the backend, the billing application should perform provisioning of the prepaid account with Asterisk, as well as offer tools for creating batch pin numbers for wholesale.