Validate at Least One TextBox in ASP.NET

using this code, you can validate that at least one textbox should be filled.

<asp:TextBox ID="txtHomePhone" runat="server"></asp:TextBox>
<asp:CustomValidator ID="cvHomePhone" runat="server" ErrorMessage="*" ClientValidationFunction="Validate" ControlToValidate="txtHomePhone"  ValidateEmptyText="true"></asp:CustomValidator>


<asp:TextBox ID="txtWorkPhone" runat="server"></asp:TextBox>
<asp:CustomValidator ID="cvWorkPhone" runat="server" ErrorMessage="*" ClientValidationFunction="Validate" ControlToValidate="txtWorkPhone"  ValidateEmptyText="true"></asp:CustomValidator>


<asp:TextBox ID="txtMobilePhone" runat="server"></asp:TextBox>
<asp:CustomValidator ID="cvMobilePhone" runat="server" ErrorMessage="*" ClientValidationFunction="Validate" ControlToValidate="txtMobilePhone"  ValidateEmptyText="true"></asp:CustomValidator>


<script language="javascript">
function Validate(sender, args)
{
    args.IsValid = false;
    if(args.Value != "")
    {
        args.IsValid = true;
    }
}
</script>