You will have to use AJAX MaskEditExtender
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
<asp:TextBox ID="TextBox1" runat="server" />
<cc1:MaskedEditExtender runat ="server"
TargetControlID="TextBox1"
Mask="999,999,999,999"
MessageValidatorTip="true"
MaskType="Number"
InputDirection="RightToLeft"
AcceptNegative="Left"
DisplayMoney="None"
ErrorTooltipEnabled="True" />
</form>
</body>
</html>