Flexible billing support in a service selection gateway (SSG)

A service selection gateway (SSG) which permits multiple access quotas associated with a pre-paid service accessed by a user. For example, the user's access may be terminated if the usage exceeds a specified time or volume of data transferred (examples of access quotas). According to another aspect, access of a service is permitted based on different tariffs. Thus, a user may be charged differently depending on the applicable tariff. In an embodiment implemented in the context of pre-paid tariffs, multiple access quotas may be received associated with the same resource, and each quota may be computed according to a corresponding tariff.