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17.7 AIN SERVICES 549Snapshot Monitoring. If SCP needs a snapshot of the line status, it setsMonitorTime to “zero.” SSP then immediately sends a Status_Reported, in whichStatusCause indicates either a “status match” or a “timeout.”17.6.6 Messages in the Information Revision FamilyThese messages enable a SCP to activate or deactivate a trigger in a SSP. Themessage parameters are listed in Table 17.6-5.Update_Request Message. This message is sent by SCP. TriggerTypeFlag(Par.36) specifies the trigger type and the state of the trigger. In a SSP, a triggeris uniquely identified by the combination of its type and its UserID (Par.l).Update_Data Message. This message is the SSP response to an Update_Request.If SSP has honored the request, the message does not contain a parameter. If SSP hasbeen unable to set the trigger to the specified state, the message includes Failure-Cause (Par.33).17.7 AIN SERVICESCompared with conventional “switch-based” services, the SCP-based AIN servicescan be designed with much more flexibility.In the first place, the service creation environment (SCE) systems usually allowthe telecom to define services that take into account the calling line—which isidentified by UserID (Par.1), CallingPartyID (Par.7), or ChargeNumber (Par.8) inall messages of the request instructions family—and the time-of-day andday-of-week that the call is made.Caller interaction also increases the flexibility of services. In the first place, servicescan be designed such that the calling party can select a particular option from aservice menu. Moreover, a service can be made available to “authorized” callersonly, by requiring the caller to enter a telecom-provided authorization code,which is checked by SCP.This section outlines a number of services that can be implemented with the triggers,messages, and parameters that have been discussed in this chapter [20]. Theexamples have been chosen as illustrations for the uses of the various triggertypes and messages, and regardless of their availability in U.S. networks. Theyare grouped into a number of categories (call management, number translation, etc.).17.7.1 AIN Outgoing Call ManagementOutgoing call management services enable residential and business customers torestrict the calls made on their lines. Some exchange-based features of this natureare already in existence. As an example, a customer can specify that calls to 900/976 numbers are to be blocked. The service is inflexible in that all 900/976 callsare either blocked or allowed.