My Sulution is as follows
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//in Caller.aspx
//--------------
<script type="text/javascript">
function openwindow() {
window.open("Callee.aspx.aspx", "windowName", "height=500, width=700");
}
</script>
<asp:Button ID="Button1" runat="server" OnClientClick="openwindow()" Text="Button" />
//In Callee.aspx
//--------------
using System.Net;
protected void Page_Load(object sender, EventArgs e)
{
string pdfPath = "D:\\Data\\Misc\\Time+registration.pdf";
WebClient client = new WebClient();
Byte[] buffer = client.DownloadData(pdfPath);
Response.ContentType = "application/pdf";
Response.AddHeader("content-length", buffer.Length.ToString());
Response.BinaryWrite(buffer);
}