3Com VCX V7122 SIP VoIP Gateway User Manual240Call Flow DescriptionFigure 86 on the previous page depicts an example of a standard PSTNÆIP call (billing-model: debit). An incoming PSTN call with a published access number reaches the VCX V7122. The VCX V7122 accepts the call (sends an Alert message). The VCX V7122 searches its internal TelÆIP Destination Number Manipulation table forthe specific prefix. When it is detected, if the ‘Prefix to Add’ column corresponds to thepredefined VXMLID parameter (in the example below: http), the VCX V7122 determinesthat the incoming call is an IVR call.Figure 87 Basic ini File VXML ParametersVXMLID = httpNumberMapTel2IP = 5394288,7,http://10.8.1.19/RadAAA01.txt The VCX V7122 loads the VoiceXML file (RadAAA01.txt) from an outbound HTTP Server(10.8.1.19) and stores it in its volatile memory. In Figure 86 it is assumed that theVoiceXML already resides in the VCX V7122. The VCX V7122 sends an Answer/Connect message. The VCX V7122 starts by playing an initial voice message. This message is composed ofan opening greeting and an interactive menu asking the caller to choose one of thefollowing options: 1 to make a call, 2 for help, 3 for operator service, 4 to exit. After pressing the digit 1, the caller is immediately prompted to enter his account number(usually the card number) and his password or PIN (personal identification number). TheVCX V7122 collects the input DTMF digits and sends an Authentication message to anoutbound RADIUS server. Only after the call is authenticated successfully (in this stage the RADIUS server returnsthe billing-model, in the above example: debit), the caller is asked to enter the number hewishes to reach, the final destination number. The gateway collects the input DTMFdigits and sends an Authorization message to the RADIUS server. The RADIUS server determines if the caller is authorized to proceed with the call andspecifies the maximum duration of the call; the VCX V7122 conveys the call to the IPnetwork and starts an internal timer. One minute before credit is exhausted (see the VXML parameter finalalerttime on page254); the finalalertaudio is played; finally, a minute later, the call is disconnected and theendaudio Voice Prompt is played.Some messages have been omitted from the above drawing for the sake of clarity.The following steps are according to the supplied VXML script.
