3Com VCX V7122 SIP VoIP Gateway User Manual114ISDN and CAS Interworking-Related ParametersTable 27 ISDN and CAS Interworking-Related Parametersini File Field NameWeb Parameter Name* Valid Range and DescriptionPlayRBTone2Tel[Play Ringback Toneto Tel]0 (Don’t play) = The ISDN / CAS gateway doesn’t play a Ringback Tone(RBT). No PI is sent to the ISDN, unless the parameter ‘Progress Indicator toISDN’ is configured differently.1 (Play) = The CAS gateway plays a local RBT to PSTN after receipt of a 180ringing response (with or without SDP).Note: Reception of a 183 response doesn’t cause the CAS gateway to play anRBT (unless ‘SIP183Behavior = 1’).The ISDN gateway functions according to the parameter‘LocalISDNRBToneSource’:If the ISDN gateway receives a 180 ringing response (with or without SDP)and ‘LocalISDNRBToneSource = 1’, it plays a RBT and sends an Alert with PI= 8 (unless the parameter ‘Progress Indicator to ISDN’ is configureddifferently).If ‘LocalISDNRBToneSource = 0’, the ISDN gateway doesn’t play an RBT andan Alert message (without PI) is sent to the ISDN. In this case, the PBX /PSTN should play the RBT to the originating terminal by itself.Note: Reception of a 183 response doesn’t cause the ISDN gateway to playan RBT; the gateway issues a Progress message (unless‘SIP183Behavior = 1’).If ‘SIP183Behavior = 1’, the 183 response is treated the same way as a 180ringing response.2 = Play according to “early media” (default).If a 180 response is received and the voice channel is already open (due to aprevious 183 early media response or due to an SDP in the current 180response), the ISDN / CAS gateway doesn’t play the RBT; PI = 8 is sent in anISDN Alert message (unless the parameter ‘Progress Indicator to ISDN’ isconfigured differently).If a 180 response is received but the “early media” voice channel is notopened, the CAS gateway plays an RBT to the PSTN; the ISDN gatewayfunctions according to the parameter ‘LocalISDNRBToneSource’:If ‘LocalISDNRBToneSource = 1’, the ISDN gateway plays an RBT and sendsan ISDN Alert with PI = 8 to the ISDN (unless the parameter ‘ProgressIndicator to ISDN’ is configured differently).If ‘LocalISDNRBToneSource = 0’, the ISDN gateway doesn’t play an RBT.No PI is sent in the ISDN Alert message (unless the parameter ‘ProgressIndicator to ISDN’ is configured differently). In this case, the PBX / PSTNshould play an RBT tone to the originating terminal by itself.Note: Reception of a 183 response results in an ISDN Progress message(unless ‘SIP183Behavior = 1’).If ‘SIP183Behavior = 1’ (183 is handled in the same way as a 180+SDP), thegateway sends an Alert message with PI = 8, without playing an RBT.In Table 27, parameters in brackets are the format in the Embedded Web Server *.
