Sending SMS with VB.NET and AT commands

In the previews post, we have learn about sending and receiving SMS using AT commands. Now using VB.NET i will be showing you how to send SMS with your window forms and discuss the process along the way. For this project I will be using VB.NET for my code behind.

Lets start with creating a project. I am naming the project "ConnSMS" and you can name your own as you wish. For this project I will be using one form which will contain all the controls that we will need to build this application. You can design your own but for the purpose of this discussion I will try to shrink all the functions into one form. Name the form and the controls as to your preference. I will be discussing each as we proceed.

Window Form:

Name the form and the controls as you prefer.  For this application we need some controls that will be used to establish connection from the computer to our GSM modem using the available serial port. The form load function will populate the combo box control with the available serial ports to which we can establish connection. I made a frame containing the text box for the recipient and the message followed by a button to send. The AT commands are then displayed to the text area at the right side of the form. The message received will then be displayed at the bottom list control. I also added a status strip to indicate current status of each event. The form and the code for this application is shown below.

ConnSMS.vb

Imports System.IO.Ports

Public Class ConnSMS
    Dim WithEvents serialport As New IO.Ports.SerialPort
    Private Declare Sub Sleep Lib "kernel32" (ByVal milsec As Long)

    Dim objport As New SMSclass

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        For i As Integer = 0 To My.Computer.Ports.SerialPortNames.Count - 1
            cmbport.Items.Add(My.Computer.Ports.SerialPortNames(i))
        Next
    End Sub

    Private Sub butSend_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butSend.Click
            If objport.SendSMS(serialport, TxtTo.Text, rtxtto.Text) Then
                lblstatStrip.Text = "Message Sent"
            Else
                lblstatStrip.Text = "Message Sending Failed"
            End If
    End Sub

    Private Sub butRead_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butLoad.Click
       
    End Sub
    Private Sub butLoad_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butLoad.Click
        Dim objShortMessageCollection = objport.ReadSMS(serialport, TxtTo.Text)
        For Each msg As ShortMessage In objShortMessageCollection

            Dim item As New ListViewItem(New String() {msg.Index, msg.Sent, msg.Sender, msg.Message})
            item.Tag = msg

            ListView1.Items.Add(item)
        Next
    End Sub
    Private Sub butConnect_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butConnect.Click
        Try
            serialport = objport.OpenPort(cmbport.Text)
            If Not serialport Is Nothing Then
                lblstatStrip.Text = "Modem is connected at PORT " & cmbport.Text & "."
            Else
                lblstatStrip.Text = "Invalid port settings."
            End If
        Catch ex As Exception
            Throw ex
        End Try
    End Sub

    Private Sub butDisconnect_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles butDisconnect.Click
        Try
            objport.ClosePort(serialport)
            lblstatStrip.Text = "Not Connected"
        Catch ex As Exception
            Throw ex
        End Try
    End Sub

    
End Class

Lets create a class that will handle the different events that we need. I will be naming this class the SMSclass.

The code for this class is shown below.

SMSclass.vb

Imports System.IO.Ports
Imports System.IO.Ports
Imports System.Threading
Imports System.Text
Imports System.Text.RegularExpressions

Public Class SMSclass

    Private Declare Sub Sleep Lib "kernel32" (ByVal milsec As Long)
    Public receiveNow As New AutoResetEvent(False)
    Shared readNow As New AutoResetEvent(False)
    Public Function OpenPort(ByVal comport As String) As SerialPort

        Dim serialport As New IO.Ports.SerialPort

        Try
            If comport <> Nothing Then
                With serialport
                    .PortName = comport
                    .BaudRate = 96000
                    .Parity = Parity.None
                    .DataBits = 8
                    .StopBits = StopBits.One
                    .Handshake = Handshake.RequestToSend
                    .ReadTimeout = 300
                    .WriteTimeout = 300
                    .Encoding = Encoding.GetEncoding("iso-8859-1")
                    .DtrEnable = True
                    .RtsEnable = True
                    .NewLine = vbCrLf
                End With
                serialport.Open()
                Return serialport
            Else
                Return serialport
            End If
        Catch ex As Exception
            Throw ex
        End Try
    End Function

    Public Sub ClosePort(ByVal serialport As SerialPort)
        Try
            serialport.Close()
        Catch ex As Exception
            Throw ex
        End Try
    End Sub

    Public Sub port_DataReceived(ByVal sender As Object, ByVal e As SerialDataReceivedEventArgs)
        If e.EventType = SerialData.Chars Then
            receiveNow.Set()
        End If
    End Sub

    Private Shared Sub DataReceived(ByVal sender As Object, ByVal e As SerialDataReceivedEventArgs)
        If e.EventType = SerialData.Chars Then
            readNow.Set()
        End If
    End Sub
    Public Function ExecCommand(ByVal port As SerialPort, ByVal strcommand As String, ByVal errmess As String)
        port.WriteLine(strcommand)
        'ConnSMS.SendMsg.Text = ConnSMS.SendMsg.Text & strcommand
        Dim input As String = ReadResponse(port, 400)
        ConnSMS.SendMsg.Text = ConnSMS.SendMsg.Text & input
        Return input
    End Function
    Public Function ReadResponse(ByVal port As SerialPort, ByVal timeout As Integer)
        Dim buff As String = ""
        Try
            Do
                Dim t As String = port.ReadExisting()
                buff = buff & t
            Loop Until buff.EndsWith(vbCrLf & "OK" & vbCrLf) Or buff.EndsWith(vbCrLf & "> ") Or buff.EndsWith(vbCrLf & "ERROR" & vbCrLf)
        Catch ex As Exception
            Throw ex
        End Try
        Return buff
    End Function
    Public Function SendSMS(ByVal port As SerialPort, ByVal PhoneNo As String, ByVal Message As String) As Boolean
        Dim isSent As Boolean = False
        Dim receivedData As String = ""

        receivedData = ExecCommand(port, "AT" & vbCr, "Unable to connect.")
        System.Threading.Thread.Sleep(200)
        receivedData = ExecCommand(port, "AT+CMGF=1" & vbCr, "Failed to set message format.")
        System.Threading.Thread.Sleep(200)
        receivedData = ExecCommand(port, "AT+CMGS=" & Chr(34) & PhoneNo & Chr(34) & vbCr, "Failed to accept phoneNo")
        System.Threading.Thread.Sleep(200)
        receivedData = ExecCommand(port, vbBack & vbBack & "FROM PICTU SMS: " & Message & Chr(26), "Failed to send message")
        System.Threading.Thread.Sleep(200)

        If receivedData.EndsWith(vbCrLf & "OK" & vbCrLf) Then
            isSent = True
        ElseIf receivedData.Contains("ERROR") Then
            isSent = False
        End If
        Return isSent

    End Function
    Public Function ReadSMS(ByVal port As SerialPort, ByVal command As String)
        Dim messages As ShrotMessageCollection = Nothing
        Dim receivedData As String = ""

        ExecCommand(port, "AT" & vbCr, "Unable to connect.")
        System.Threading.Thread.Sleep(200)
        ExecCommand(port, "AT+CMGF=1" & vbCr, "Failed to set message format.")
        System.Threading.Thread.Sleep(200)
        ExecCommand(port, "AT+CSCS=" & Chr(34) & "PCCP437" & Chr(34), "Failed to set character set.")
        System.Threading.Thread.Sleep(200)
        ExecCommand(port, "AT+CPMS=" & Chr(34) & "ME" & Chr(34), "Failed to select message storage.")
        System.Threading.Thread.Sleep(200)
        receivedData = ExecCommand(port, "AT+CMGL=" & Chr(34) & "REC UNREAD" & Chr(34), "Failed to read all message.")
        System.Threading.Thread.Sleep(200)
        messages = ParseMessages(receivedData)

        If Not messages Is Nothing Then
            Return messages
        Else
            Return Nothing
        End If
    End Function
    Public Function ParseMessages(ByVal input As String) As ShrotMessageCollection
        Dim messages As New ShrotMessageCollection()
        Try
            Dim r As New Regex("\+CMGL: (\d+),""(.+)"",""(.+)"",(.*),""(.+)""\r\n(.+)\r\n")
            Dim m As Match = r.Match(input)
            While m.Success
                Dim msg As New ShortMessage()
                'msg.Index = int.Parse(m.Groups[1].Value);
                msg.Index = m.Groups(1).Value
                msg.Status = m.Groups(2).Value
                msg.Sender = m.Groups(3).Value
                msg.Alphabet = m.Groups(4).Value
                msg.Sent = m.Groups(5).Value
                msg.Message = m.Groups(6).Value
                messages.Add(msg)

                m = m.NextMatch()

            End While
        Catch ex As Exception
            Throw ex
        End Try
        Return messages
    End Function
End Class

I also created an class named "ShortMessages.vb". This will contain the properties of the SMS and be used in reading the SMS from the GSM modem. Another object will hold the value for the collection of SMS. To do this I added another class named "ShortMessageCollection.vb" which inherits the "ShortMessage.vb" class.

ShortMessage.vb

Public Class ShortMessage
    Public Index As String
    Public Status As String
    Public Sender As String
    Public Alphabet As String
    Public Sent As String
    Public Message As String
End Class

ShrotMessageCollection.vb

Public Class ShrotMessageCollection
    Inherits List(Of ShortMessage)

End Class

That's it! We are done with this project. Try to make your own application and see for your self. I hope that this post can guide you along the way. The project might have some bugs though. I have not tested it yet completely but the functions I have made seems to work for me. You can contribute by posting your comments and suggestions to improve this subject. I would be glad to here your suggestions. I will wrap things up and try to create a video of this project at run-time. 

Watch out for more. Cheers!