I dived into IVR recently for a demo application that records voices for further listening, sort of an audio repository. It was fun and a great learning experience. During the phase I learnt VXML and how to navigate users on key-presses from one menu to another etc. I used VXML with ASP.NET (C#) to provide creating new account, login, saving a new audio and listening to it again, with MS SQL 2005 as backend. So here is some information about IVR and how you can start developing.

In the next post insha ALLAH I would share some parts of the script that I used to interact with ASP.NET and VXML.

What is IVR?

Excerpt taken from: http://www.voxeo.com/library/

IVR – short for Interactive Voice Response – is a technology that automates interactions with telephone callers. Enterprises are increasingly turning to IVR to reduce the cost of common sales, service, collections, inquiry and support calls to and from their company.

Historically, IVR solutions have used pre-recorded voice prompts and menus to present information and options to callers, and touch-tone telephone keypad entry to gather responses. Modern IVR solutions also enable input and responses to be gathered via spoken words with voice recognition.

IVR solutions enable users to retrieve information including bank balances, flight schedules, product details, order status, movie show times, and more from any telephone. Additionally, IVR solutions are increasingly used to place outbound calls to deliver or gather information for appointments, past due bills, and other time critical events and activities.

IVR, CTI, and Computer Telephony developers create applications that combine telephone and computer systems. Historically, these applications have been built with a wide variety of telephony APIs, components, and script languages.

These include:

• Dialogic R4 and GlobalCall - two popular, C-centric APIs that work with Dialogic/Intel telephony cards.
• TAPI and JTAPI – two abstract telephony APIs for Windows and Java, currently supported by around 20% of the telephony market.
• ECTF S.100 – a complex but comprehensive telephony API supported by around 10% of the telephony market.
• ActiveX Controls – such as Visual Voice and VBVoice that simplify Dialogic and TAPI API development complexity.
• Proprietary IVR languages – each unique to the IVR platform they run on.

All of these telephony programming solutions suffer from three common problems: None are widely adopted standards; all are limited to a subset of platforms and operating systems; and all were designed to requirements that pre-date modern web-based solutions.

Over the last five years, the telephony industry has turned to two XML and web based standards for telephony platforms: VoiceXML and CCXML. VoiceXML and CCXML are industry standards from the World Wide Web Consortium (W3C) – the same successful standards body that created HTML, XML, and HTTP.

VoiceXML defines a markup based standard for Interactive Voice Response (IVR), including prompts, recording, touch-tone entry, voice recognition, and text to speech; while CCXML markup provides the foundation for call initiation, control, switching, routing, conferencing, and call center integration.

VoiceXML and CCXML solutions run on an increasing variety of IVR, CTI, and Computer Telephony servers, products, and boards. Furthermore, because these standards are based on XML and HTTP, they bring with them the immense power and value of web technologies.

Excerpt taken from: http://www.voxeo.com/library/

Suppose you have 2 controls 1.LinkButton 2. Label in Grid’s template column and you want to make either of them visible based upon a column say “Status” that may be bit, nvarchar etc in the database, anyways thats what I do:

Before

<asp:GridView ID=”grdTasks” runat=”server” AllowPaging=”false” Visible=”true”
               AutoGenerateColumns=”false”
               OnRowCommand=”grdTasks_OnRowCommand” OnDataBinding=”grdTasks_OnDataBinding”
               OnRowDataBound=”grdTasks_OnRowDataBound”>
    <Columns>
       <asp:BoundField DataField=”ID” SortExpression=”ID” HeaderText=”ID” Visible=”true” />
        <asp:BoundField DataField=”ItemDescription” SortExpression=”ItemDescription” HeaderText=”Task” Visible=”true” />

        <asp:TemplateField HeaderText=”Status”>
            <ItemTemplate>
             <asp:LinkButton ID=”lb” runat=”server” CommandArgument=”<%#ID%>” CausesValidation=”false” Text=”Pending” ForeColor=”blue”></asp:LinkButton>
             <asp:Label ID=”lbl” runat=”server” Font-Size=”X-Small” Text=”Complete” ForeColor=”green”></asp:Label>
            </ItemTemplate>
         </asp:TemplateField>
      <asp:BoundField DataField=”ItemStatus” SortExpression=”ItemStatus” HeaderText=”Issues” Visible=”true” />
   </Columns>
</asp:GridView>

After

<asp:LinkButton ID=”lb” runat=”server” CommandArgument=”<%#ID%>” CausesValidation=”false” Text=”Pending” ForeColor=”blue” Visible=’<%# Convert.ToBoolean(Eval(“Status”)) %>’ ></asp:LinkButton>

<asp:Label ID=”lbl” runat=”server” Font-Size=”X-Small” Text=”Complete” ForeColor=”green”
Visible=’<%# !Convert.ToBoolean(Eval(“Status”)) %>’></asp:Label>
Â
Simple but works GOOD !

This error is really annoying and many of us face this quite oftenly. This may occur when you add a new item in Dropdown (with clientcode/ javascript) that is populated from server-side and postback occurs, binding a Grid and adding controls dynamically and clicking but my case was:

if page is not fully loaded and the _EventValidaiton hidden field is not present by that time then clicking a button or a postback was raising this exception. Simplest solution that I found after spending days was to install .NET framerwork 2.0′s SP2 which can be intsalled as part of framework 3.5 SP1 (besides writing this post I am also searching to get 2.0 SP2 as a standalone intsall). Well if thats the problem I hope you can solve this with SP2 intalled and can try methods listed here:

http://blogs.msdn.com/tom/archive/2008/03/14/validation-of-viewstate-mac-failed-error.aspx

After intalling I observed that noe EventValidation was rendering at top and controls after that. This fix ensures that EventValidation has the hash of every control before they are displayed.

Note: Many posts suggest to disable EnableEventValidation attribute of page directive but folks please try to avoid it as much as you can.