How to send SMS to multiple users at a single click in c#.net?

//Use this code..

public void send(string message, string no)
{

HttpWebRequest myReq =
// Eg: (HttpWebRequest)WebRequest.Create("http://ubaid.tk/sms/sms.aspx?uid=" + uid + "&pwd=" + password +
//"&msg=" + message + "&phone=" + no + "&provider=way2sms");
(HttpWebRequest)WebRequest.Create("puturlink = "+"UrUsername"+ "&password=" + "UrPassword" + "&sender=" +"UrSenderID"+ "&to=" +no+ "&message=" + message+ "&reqid=1&format={json|text}&route_id=route+id&callback=Any+Callback+URL&unique=1&sendondate=" +"10-10-2014T05:17:52"+"");
HttpWebResponse myResp = (HttpWebResponse)myReq.GetResponse();
System.IO.StreamReader respStreamReader = new System.IO.StreamReader(myResp.GetResponseStream());
string responseString = respStreamReader.ReadToEnd();
respStreamReader.Close();
myResp.Close();
}

//Button Click code
protected void btn_send_Click(object sender, EventArgs e)
{

send(txt_message.Text, txt_mobile.Text);

ScriptManager.RegisterStartupScript(this, this.GetType(), "popup", "alert('sms sent successfully...');", true);

}