/mcpQuality of Service for Voice over IP Resource Reservation Protocol 23 QoSVoIP.mif alerting state. A normal disconnect is initiated when an H.323 RELEASE COMPLETE message is sent after the call is connected. At that point, the gateways tear down their reservations by sending RSVP PATH TEAR and RESV TEAR messages. If at least one RSVP reservation fails, you can configure a voice gateway to take the following actions: • The voice gateway can report the call failure to the user or the switch that delivered the call. • The call can be rerouted through another path. • The call can be connected with best-effort QoS. This last behavior is possible because the terminating gateway knows which QoS is acceptable for the call from its own configuration and the value included by the originating gateway in the H.323 SETUP message. If the terminating gateway and the originating gateway request a nonbest-effort QoS and at least one reservation fails, the call will proceed as best-effort only if the originating gateway and the terminating gateway are willing to accept best-effort service. Call release and call rerouting are possible if one of the two voice gateways will not accept best-effort service. If you configure the gateway to reject the call and report the failure, CAS trunks and analog lines generate a fast busy signal. On CCS PRI trunks, a Q.931 DISCONNECT message with a cause “QoS unavailable” (49) will be generated. Figure 7 shows the details of a call that is rejected because the reservation initiated from the terminating gateway failed. Figure 7 Call Failing RSVP CAC Because of Terminating Gateway Reservation Failure SETUP Call Setup Initiated OGW TGW Reservation Initiated Call Disconnect Initiated OGW TGW Reservation Initiated OGW Originating Gateway TGW Terminating Gateway H.323 Call Setup Signaling RSVP Reservation Initiated by TGW RSVP Reservation Initiated by OGW OGW TGW PATH PATH RESV TEAR RESV CONFIRMATION RELEASE COMPLETE PATH TEAR CALL PROCEEDING PATH RESV PATH TEAR PATH TEAR RESV OGW TGW Reservation Teardown Initiated OGW TGW Reservation Teardown Initiated 60064