try this :
public void SendSms(string mobileNo, string msg)
{
string userid = "UserID";
string pass = "Password";
string senderid = "ID";
string sendPhone = mobileNo;
string sendMsg = msg;
string url ="http://u.vsms.in/SendSMS/sendmsg.php?uname=" + userid + "&pass=" + pass + "&send=" + senderid + "&dest=" + sendPhone + "&msg=" + sendMsg +"";
WebRequest myRequest = null;
HttpWebResponse myResponse = null;
string result = "";
myRequest = WebRequest.Create(url);
myResponse = (HttpWebResponse)myRequest.GetResponse();
Stream stream = myResponse.GetResponseStream();
Encoding ec = System.Text.Encoding.GetEncoding("utf-8");
StreamReader reader = new System.IO.StreamReader(stream, ec);
result = reader.ReadToEnd();
if (result.Contains("Submitted"))
{
result = "Success Sending :" + sendPhone;
}
else if (result.Contains("105"))
{
result = "Invalid Number :" + sendPhone;
}
reader.Close();
stream.Close();
if (myResponse != null)
{
myResponse.Close();
}
}