The temporal solution is to change the type attribute of the RadNumericTextBox input to "tel". This can be done in the OnLoad client event of the control:


<script>
    function OnLoad(sender, args) {
            sender.get_element().setAttribute("type", "tel");
    }
</script>
<telerik:RadNumericTextBox  RenderMode="Lightweight" runat="server" ID="RadNumericTextBox1" Width="190px" Value="1" EmptyMessage="Enter units count" MinValue="0"  ShowSpinButtons="true" NumberFormat-DecimalDigits="0">
    <ClientEvents OnLoad="OnLoad" />
</telerik:RadNumericTextBox><br />