r a call are first admitted, and once the end-to-end negotiation is completed, the resources are activated. The two-phase model serves the following purposes: (1) conserving network resources until a complete end-to-end connection has been established; (2) performing policy checks and admission control on resources as quickly as possible, and in particular, before informing the other side of a connection request; and (3) preventing several potential theft-of-service scenarios. Active service flows: a service flow that has a non-null ActiveQoSParamSet with committed resources by the BS. An admitted service flow may be activated by providing an ActiveQoSParamSet, signaling the resources actually desired at the current time. A service flow may be provisioned and immediately activated. Alternatively, a service flow may be created dynamically and immediately activated. In this case, two-phase activation can be skipped and the service flow is available for immediate use upon authorization. The provisioning of service flows is outside of the scope of the standard. During provisioning, a service flow is instantiated, i.e., an SFID and a provisioned type are assigned. For some service flows, a dynamic service addition is activated by the network entry procedure. The service flows are enabled following the transfer of the operational parameters. In this case, the service flow type may change to "admitted" or "active". Thus, the service flow is mapped onto a certain connection. Service flow encodings contain either a full definition of service attributes or a service class name. A service class name is an ASCII string, which is known to the BS and indirectly specifies a set of QoS parameters. 5.2.3 Service Flow Classification Classification is the process by which a MAC SDU is mapped onto a particular transport connection for transmission between MAC peers. The mapping process associates a MAC SDU with a transport connection, which also creates an association with the service flow characteristics of that connection. This pr