vb.net AT commands to send SMS

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Introduction

This code provided allows to send SMS from the PC to any mobile with the help of GSM modem or any GSM compatible mobile.

Background

Basically I am making use of AT commands , which are AtTention Commands which are used for  communication between the computer and the modem.

Microsoft windows provides witha software called Hyperterminal which is available through thispath.

Start-> Programs-> Accessories->communications->hypertreminal

AT commands can be typed here. Hypertreminal communicates directly with the modem /mobile connected and instructs the modem. It also gives responses back as OK or error etc. But if we have a application where we need to send SMS after a specific set of actions, then hypertreminal is not useful, since it requiers manual typing. You need to select the COm port on which modem/mobile is connected.(port can be serial port for modem or USB port for mobile).

The code given does this.If any doubs are there you can contact me on the forum below

Using the Code

First, connect modem or mobile. Go to device manager and under Ports options check for which COM (e.g. COM3 , COM4 etc)port your modem/mobile has been connected to.

//
// if COM3 is shown in device manager then put COM4 in foll statement
//
    Dim SMSEngine As New SMSCOMMS("COM4")

'the port needs to be initialised

SMSPort = New SerialPort
        With SMSPort
            .PortName = COMMPORT
            .BaudRate = 19200
            .Parity = Parity.None
            .DataBits = 8
            .StopBits = StopBits.One
            .Handshake = Handshake.RequestToSend
            .DtrEnable = True
            .RtsEnable = True
            .NewLine = vbCrLf
        End With 


        'this is  the set of AT commands to be written on serial port

            SMSPort.WriteLine("AT")
            'set command message format to text mode(1)
            SMSPort.WriteLine("AT+CMGF=1" & vbCrLf) 
            'set service center address (which varies for service providers (idea, airtel))
            SMSPort.WriteLine("AT+CSCA=""+919822078000""" & vbCrLf)             
            ' enter the mobile number whom you want to send the SMS
            SMSPort.WriteLine("AT+CMGS=  + TextBox1.text + " & vbCrLf) 
            _ContSMS = False
            SMSPort.WriteLine("+ TextBox1.text +" & vbCrLf & Chr(26)) 'SMS sending

    Dim i As Integer
    Private Sub Button1_Click(ByVal sender As System.Object,
       ByVal e As System.EventArgs) Handles Button1.Click

        SMSEngine.Open() 'open the port
        SMSEngine.SendSMS() 'send the SMS

    End Sub

class SMSCOMMS is defined in the code. I have tried this code with only nokia mobiles like nokia 5310, nokia 3500 etc. ALso i have tried sending sms from airtel provider to idea also. It works fine. Download the code. Its simple n explained with comments. 

Points of Interest

Programming in mobile communication, serial port interfacing, TAPI programming in.net

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)