11 Understanding Credit Authorization Models

RFC 4006 defines two basic types of credit authorization models:

• Credit authorization with unit reservation.

• Credit authorization with direct debiting.

Credit authorization with unit reservation can be performed with either event-based or session-based charging events. Credit authorization with direct debiting uses immediate charging events. In both models, the CTF requests credit authorization from the OCF prior to delivering services to the end user.

The sections that follow describe each model in more detail.