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Using the WinAgents TFTP Server for Cisco IVR Applications
IVR (Interactive Voice Response) technology is widely used for providing IP-telephony prepaid services. IVR technology gets the VoIP gateway to run a special program that is an IVR script. This script enables the playing of messages composed of audio fragments stored at the TFTP server for the user.
To deploy the IVR application used to provide IP-telephony prepaid services, the following components are required:
- IP-telephony gateway (Cisco router) – receives user calls from POTS and translates them in the VoIP network
- RADIUS server supporting Cisco VSA (vendor-specific attributes) – authorizes user cards and sends information regarding account and available call length to the gateway or to the gatekeeper
- TFTP server – stores audio fragments played by the system
- Gatekeeper (optional) – – consolidates information concerning call routes.
Diagram 1. Cisco-based prepaid telephony solution.
The WinAgents TFTP Server has been designed to be used in such solutions. WinAgents TFTP Server is Windows-based and this means the 24x7 mode of system operation is available. Also, the server possesses a number of advantages over standard servers, enabling its operation in critical IVR applications. The server can transfer files larger than 33 MB, and this makes it possible to use longer audio fragments. Furthermore, the server supports the increase of process priority mode that makes for successful “rush-hour” operation.
Call processing in Cisco IVR goes as follows:
- A user calls the IP-telephony gateway.
- The IVR application at the gateway receives the call. The appliance downloads a file requesting entry of the card number from the TFTP server, and displays the request.
- The user enters the card number.
- The IVR application sends a request for authorization to the RADIUS server. The RADIUS server provides access confirmation by sending the card’s current balance in the form of VSA attributes.
- The IVR application formulates a message containing account balance information by acquiring audio fragments from the TFTP server, and plays this message to the user.
- The user enters the phone number to which the call is to be placed.
- The IVR application sends a second authorization request to the RADIUS server and transfers the phone number in the form of a VSA parameter. The RADIUS server formulates a reply based on current rates, and provides the available call length value as a VSA parameter.
- The IVR application formulates a message that provides the available call length by using audio fragments from the TFTP server, and plays this message to the user.
- The VoIP gateway connects to the remote party and the user begins talking.