V7122 Gateway User Guide 257PSTN Fallback as a Special Case of Alternative RoutingThe purpose of the PSTN Fallback feature is to enable the gateway to redirect PSTNoriginated calls back to the legacy PSTN network if a destination IP route is found unsuitable(disallowed) for voice traffic at a specific time.To enable PSTN fallback, assign the IP address of the gateway itself as an alternative routeto the desired prefixes. Note that calls (now referred to as IP to Tel calls) can be re-routed toa specific trunk group using the Routing parameters.Relevant ParametersThe following parameters (described in Table 44) are used to configure the AlternativeRouting mechanism: AltRoutingTel2IPEnable AltRoutingTel2IPMode IPConnQoSMaxAllowedPL IPConnQoSMaxAllowedDelayCall Detail ReportThe Call Detail Report (CDR) contains vital statistic information on calls made by thegateway. CDRs are generated at the end and (optionally) at the beginning of each call(determined by the parameter ‘CDRReportLevel’) and sent to a Syslog server. Thedestination IP address for CDR logs is determined by the parameter ‘CDRSyslogServerIP’.The following CDR fields are supported:Table 51 Supported CDR FieldsField Name DescriptionCid Board’s Logic Channel NumberCallId H.323/SIP Call IdentifierTrunk Physical Trunk NumberBChan Selected B-ChannelConId H.323/SIP Conference IDTG Trunk Group NumberEPTyp Endpoint TypeOrig Call Originator (IP, Tel)SourceIp Source IP Address
