'This is a ASP.Net using VB.Net as CodeBehind 
Imports System
Imports System.IO
Imports System.Net
Imports System.Text

Partial Class testvbsample
    Inherits System.Web.UI.Page

    Dim objProxy As WebProxy = Nothing
 
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim strPostBody As String
        Dim strPostResponse As String

        'Give The Respective Variable Values
        Dim userName As String = "UserName" 'Enter Your User Name
        Dim password As String = "Password" 'Enter Your Password
        Dim mobileNumber As String = "9199xxxxx,919xxxxxxx,........" 'Enter Multiple Mobile Numbers With Comma Seperated'
        Dim message As String = "MESSAGE" 'Enter Your Message
        Dim senderid As String = "SENDERID" ' Enter Your Senderid
        Dim messageType As String = "N" ' Enter Your Message Type As N for Normal Message, O for Other Laungauge Sms
        Dim deliveryReports As Char = "Y" ' if U want To Know Delivery Reports Enter Y it Gives JOBID Otherwise N 

        '****If U R Behind The Proxy Server Uncomment And Give Below Details *****
        'objProxy = New WebProxy("Proxy Ip Adress", PortNumber)

        'Call sendSMS Method For Sending The Sms's
        message = Server.UrlEncode(message)
        strPostBody = "User=" & userName & "&passwd=" & password & "&mobilenumber=" & mobileNumber & "&message=" & message & "&sid=" & senderid & "&mtype=" & messageType & "&DR=" & deliveryReports
        strPostResponse = sendSMS(strPostBody)
        Response.Write(strPostResponse)

    End Sub
    Function sendSMS(ByVal stringPost) As String
        sendSMS = ""

        Dim objWebRequest As HttpWebRequest = Nothing
        Dim objWebResponse As HttpWebResponse
        Dim objStreamWriter As StreamWriter = Nothing
        Dim objStreamReader As StreamReader = Nothing
        Try
            Dim stringResult As String
            objWebRequest = CType(WebRequest.Create("http://www.smscountry.com/smscwebservice.asp"), HttpWebRequest)
            objWebRequest.Method = "POST"
            If Not objProxy Is Nothing Then objWebRequest.Proxy = objProxy
            objWebRequest.ContentLength = stringPost.Length
            objWebRequest.ContentType = "application/x-www-form-urlencoded"
            objStreamWriter = New StreamWriter(objWebRequest.GetRequestStream())
            objStreamWriter.Write(stringPost)
            objStreamWriter.Flush()
            objStreamWriter.Close()
            objWebResponse = CType(objWebRequest.GetResponse(), HttpWebResponse)
            objStreamReader = New StreamReader(objWebResponse.GetResponseStream())
            stringResult = objStreamReader.ReadToEnd()
            objStreamReader.Close()
            'Getting Response
            Return (stringResult)  'jobid
        Catch ex As Exception
            Return (ex.ToString)
        Finally
            If Not objStreamWriter Is Nothing Then
                objStreamWriter.Close()
            End If
            If Not objStreamReader Is Nothing Then
                objStreamReader.Close()
            End If
            objWebRequest = Nothing
            objWebResponse = Nothing
            objProxy = Nothing
        End Try
    End Function
End Class