C#

using System;
using System.Collections.Generic;
using System.Collections;
using System.Text;
using System.IO;
using System.Windows.Forms;
using System.IO.Ports;
using System.Threading;
using System.ComponentModel;
using System.Data;
using System.Drawing;


namespace SMSTest
{
    class SMSModem 
    {


        public ArrayList PortNameContainer = new ArrayList();
        public ArrayList BaudRateContainer = new ArrayList();
        public ArrayList DataBitContainer = new ArrayList();
        public ArrayList PhoneNumberContainer = new ArrayList();
        public ArrayList SMSCetreNoContainer = new ArrayList();

        SerialPort serialPort1 = new SerialPort();
        private string config_file = "C:/config.txt";
       // public string PhoneNumber;
        private string ServiceCentreNo;
        public int NumberOfLines = 0;


        public bool ModemConfig()
        {
            try
            {
                string line;
                TextReader tr = new StreamReader(config_file);
                System.IO.StreamReader objReader;
                objReader = new System.IO.StreamReader(config_file);


                while ((line = tr.ReadLine()) != null)
                {
                    NumberOfLines++;
                }


                string[] ListLines = new string[NumberOfLines];

                for (int i = 0; i < NumberOfLines; i++)
                {
                    ListLines[i] = objReader.ReadLine();
                    string[] values = ListLines[i].Split(new char[] { '$', '#' });
                    string[] PortSplit = values[0].Split(new char[] { ':', '#' });
                    string PortName = PortSplit[1];

                    //********Reading Baud Rate*********
                    string[] BaudSplit = values[1].Split(new char[] { ':', '#' });
                    int BaudRate = Convert.ToInt32(BaudSplit[1]);

                    //******READING DATA BITS**********
                    string[] BitsSplit = values[2].Split(new char[] { ':', '#' });
                    int DataBits = Convert.ToInt32(BitsSplit[1]);

                    //********READING SIM PHONE NUMBER********
                    string[] NumberSplit = values[3].Split(new char[] { ':', '#' });
                    string PhoneNumber = NumberSplit[1];

                    //******READ SERVICE CENTRE NUMBER*********
                    string[] SerNumberSplit = values[4].Split(new char[] { ':', '#' });
                    ServiceCentreNo = SerNumberSplit[1];

                    //******Setting Modem Configuration********

//I want to save the below configuration as a modem object into an array! Currently i am saving the //individual settings to an array list and when ever i needs the modem to do something, i am //reconfiguring the modem again using the values that i get from the array list! So i cant do parrallel //sending with multiple modems!
                    serialPort1.PortName = PortName;
                    serialPort1.BaudRate = BaudRate;
                    serialPort1.DataBits = DataBits;
                    serialPort1.Handshake = Handshake.RequestToSend;
                    serialPort1.Parity = Parity.None;
                    serialPort1.StopBits = StopBits.One;
                    serialPort1.DtrEnable = true;

                    //**********AT CONFIG***********
                    serialPort1.Open();
                    serialPort1.Write("AT \r\n");
                    Thread.Sleep(5);
                    serialPort1.Write("AT+CMGF=1 \r\n");
                    Thread.Sleep(5);
                    serialPort1.Write("AT+CNMI=1,2,0,0,0 \r\n");
                    Thread.Sleep(5);
                    serialPort1.Write("AT+CMEE=0 \r\n");
                    Thread.Sleep(5);
                    serialPort1.Close();

  //****Adding value to array list
                    PortNameContainer.Add(Convert.ToString(PortName));
                    BaudRateContainer.Add(BaudRate);
                    DataBitContainer.Add(DataBits);
                    PhoneNumberContainer.Add(PhoneNumber);
                    SMSCetreNoContainer.Add(ServiceCentreNo);
                }//end while
            }//end try

            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
                return false;
            }
            return true;
        }
 
        
        
    }
        
}

using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.IO.Ports;
using System.Windows.Forms;
using System.Threading;


namespace SMSTest
{
    
    class SMSManager
    {
        private SMSModem mdm = new SMSModem();
        //*****************SEND SMS********************************
        private SerialPort serialPort1 = new SerialPort();
        private int index;
        private string result;
        private void PortInitialise() //initialise port with the reveived modem number
        {
            serialPort1.PortName = Convert.ToString(mdm.PortNameContainer[index]);
            serialPort1.BaudRate = Convert.ToInt32(mdm.BaudRateContainer[index]);
            serialPort1.DataBits = Convert.ToInt32(mdm.DataBitContainer[index]);
            serialPort1.Handshake = Handshake.RequestToSend;
            serialPort1.Parity = Parity.None;
            serialPort1.StopBits = StopBits.One;
            serialPort1.DtrEnable = true;
        }
        
        public string SendSMS(string MPN, string RPN, string text)
        {
            try
            {
            
            mdm.ModemConfig();
            if (mdm.PhoneNumberContainer.Contains(MPN))
            {
                index = mdm.PhoneNumberContainer.IndexOf(MPN);
                //****CALL CONFIG: TO SEND SMS****
                PortInitialise();
                serialPort1.Open();
                string ServiceCentre = Convert.ToString(mdm.SMSCetreNoContainer[index]);
                //*************Write AT to the ports to send sms
                serialPort1.WriteLine("AT+CMGF=1;+CSCA=\"" + ServiceCentre + "\";+CMGS=\"+65" + RPN + "\"\r\n");
                System.Threading.Thread.Sleep(40);
                serialPort1.Write(text);
                char[] arr = new char[1];
                arr[0] = (char)26; //ascii value of Ctrl-Z
                serialPort1.Write(arr, 0, 1);
                System.Threading.Thread.Sleep(3000);
                string data = serialPort1.ReadExisting();
                result = "Message Sent";
                serialPort1.Close();
            }//end if
        }//end of try
        catch(Exception e)
        {
            result = "Message sending failed :" + e.Message;
        }
        return result;
        }
        //********************END OF SEND SMS****************************
                
    }


}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace SMSTest
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
            

        private void button1_Click(object sender, EventArgs e)
        {
            SMSManager sm = new SMSManager();

            //************SEND SMS***********
            string msg = sm.SendSMS("+6581563840", "82083412", "test");
            MessageBox.Show(msg);
            //*******************************
           
        }

        private void Form1_Load(object sender, EventArgs e)
        {
        }
    }
}