How to Answer Call using Java Communication Api with GSM Modem Java

Question

I have successfully Implemented Java Api and Started to Send SMS and Dial Calls.But I am finding it impossible to answer the incoming call .I have tried the RI event ( serialPort.notifyOnRingIndicator(true);).But it is not firing only DATA_AVAILABLE event is Firing

1. I have tried reading input buffer and On detecting "RING" send ATA Command But its not working not able to detect RING even though when written dircetly to Console from InputStream it Contains RING
2. Tried to send ATA Command when FROM Case RI(Ring Indicator) in serial event handler .

I am trying to implement An IVR System .How to send ATA command in this scenario , How to detect the RING and Why Is the RI event Not firing

Code

package sample;



    import java.io.*;
    import java.util.*;

    import gnu.io.*;

    import java.io.*;

    import javax.sound.sampled.AudioInputStream;
    import javax.sound.sampled.AudioSystem;
    import javax.sound.sampled.Clip;
    import javax.sound.sampled.LineUnavailableException;
    import javax.sound.sampled.UnsupportedAudioFileException;

    import org.apache.log4j.chainsaw.Main;

    import sun.audio.*;

    public class GSMConnect implements SerialPortEventListener, 
     CommPortOwnershipListener {

     private static String comPort = "COM6"; // This COM Port must be connect with GSM Modem or your mobile phone
     private String messageString = "";
     private CommPortIdentifier portId = null;
     private Enumeration portList;
     private InputStream inputStream = null;
     private OutputStream outputStream = null;
     private SerialPort serialPort;
     String readBufferTrial = "";
     /** Creates a new instance of GSMConnect */
     public GSMConnect(String comm) {

       this.comPort = comm;

     }

     public boolean init() {
       portList = CommPortIdentifier.getPortIdentifiers();
       while (portList.hasMoreElements()) {
         portId = (CommPortIdentifier) portList.nextElement();
         if (portId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
           if (portId.getName().equals(comPort)) {
               System.out.println("Got PortName");
             return true;
           }
         }
       }
       return false;
     }

     public void checkStatus() {
       send("AT+CREG?\r\n");
     }

     public void dial(String phoneNumber) {
       try {
    //dial to this phone number

         messageString = "ATD" + phoneNumber + ";\r\n";
         outputStream.write(messageString.getBytes());
         System.out.println("Called ");
       } catch (IOException e) {
         e.printStackTrace();
       }
     }

     public void send(String cmd) {
       try {
         outputStream.write(cmd.getBytes());
       } catch (IOException e) {
         e.printStackTrace();
       }
     }

     public void sendMessage(String phoneNumber, String message) {
           char quotes ='"';
       send("AT+CMGS="+quotes + phoneNumber +quotes+ "\r\n");
       try {
        Thread.sleep(2000);
    } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
        //   send("AT+CMGS=\""+ phoneNumber +"\"\r\n");
       send(message + '\032');
       System.out.println("Message Sent");
     }

     public void hangup() {
       send("ATH\r\n");
     }
     public void welcomeMessage(){

         // open the sound file as a Java input stream
            String gongFile = "C:\\Users\\SACHIN\\Desktop\\7001110.mp3";
            InputStream in;
            try {
                in = new FileInputStream(gongFile);
                 // create an audiostream from the inputstream
               // AudioStream audioStream = new AudioStream(in);
                // play the audio clip with the audioplayer class
               // AudioPlayer.player.start(audioStream);
                Clip clip = AudioSystem.getClip();
                AudioInputStream inputStream = AudioSystem.getAudioInputStream(
                  Main.class.getResourceAsStream(gongFile));
                clip.open(inputStream);
                clip.start(); 
            } catch (IOException | UnsupportedAudioFileException | LineUnavailableException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }





     }
     public void connect() throws NullPointerException {
       if (portId != null) {
         try {
           portId.addPortOwnershipListener(this);

           serialPort = (SerialPort) portId.open("MobileGateWay", 2000);
           serialPort.setSerialPortParams(115200,SerialPort.DATABITS_8,SerialPort.STOPBITS_1,SerialPort.PARITY_NONE);
         } catch (PortInUseException | UnsupportedCommOperationException e) {
           e.printStackTrace();
         }

         try {
           inputStream = serialPort.getInputStream();
           outputStream = serialPort.getOutputStream();

         } catch (IOException e) {
           e.printStackTrace();
         }

         try {
           /** These are the events we want to know about*/
           serialPort.addEventListener(this);
           serialPort.notifyOnDataAvailable(true);
           serialPort.notifyOnRingIndicator(true);
         } catch (TooManyListenersException e) {
           e.printStackTrace();
         }

    //Register to home network of sim card

         send("ATZ\r\n");

       } else {
         throw new NullPointerException("COM Port not found!!");
       }
     }

     public void serialEvent(SerialPortEvent serialPortEvent) {
       switch (serialPortEvent.getEventType()) {
         case SerialPortEvent.BI:
         case SerialPortEvent.OE:
         case SerialPortEvent.FE:
         case SerialPortEvent.PE:
         case SerialPortEvent.CD:
         case SerialPortEvent.CTS:
         case SerialPortEvent.DSR:
         case SerialPortEvent.RI:
             System.out.println("Ringing");

        /*try {
            Thread.sleep(5000);
            send("ATA");
        } catch (InterruptedException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }*/
        break;
         case SerialPortEvent.OUTPUT_BUFFER_EMPTY:
         case SerialPortEvent.DATA_AVAILABLE:

           byte[] readBuffer = new byte[2048];
           try {
             while (inputStream.available() > 0) 
             {
               int numBytes = inputStream.read(readBuffer);

               System.out.print(numBytes);
               if((readBuffer.toString()).contains("RING")){
               System.out.println("Enter Inside if RING Loop");    


               welcomeMessage();
               }
             }
             //readBufferTrial=readBufferTria;//+new String(readBuffer)+new Date();
             //print response message
             System.out.print(new String(readBuffer));
           } catch (IOException e) {
           }
           break;
       }
     }
     public void outCommand(){
         System.out.print(readBufferTrial);
     }
     public void ownershipChange(int type) {
       switch (type) {
         case CommPortOwnershipListener.PORT_UNOWNED:
           System.out.println(portId.getName() + ": PORT_UNOWNED");
           break;
         case CommPortOwnershipListener.PORT_OWNED:
           System.out.println(portId.getName() + ": PORT_OWNED");
           break;
         case CommPortOwnershipListener.PORT_OWNERSHIP_REQUESTED:
           System.out.println(portId.getName() + ": PORT_INUSED");
           break;
       }

     }
     public void closePort(){

        serialPort.close(); 
     }

     public static void main(String args[]) {
       GSMConnect gsm = new GSMConnect(comPort);
       if (gsm.init()) {
         try {
             System.out.println("Initialization Success");
           gsm.connect();
           Thread.sleep(5000);
           gsm.checkStatus();
           Thread.sleep(5000);
           System.out.println("Before Auto Answer");
           gsm.send("ATS0=1");
           Thread.sleep(7500);
           System.out.println("After Auto Answer set");

        //   gsm.sendMessage("87SSSXXX9105", "Trial Success ");
           Thread.sleep(5000);
         //   gsm.sendMessage("+919633XXXXX", "Third Msg");
         //  Thread.sleep(1000);
         //  gsm.dial("87SSSXXX9105");
         //  gsm.dial("87SSSXXX9105");
         //  Thread.sleep(1000);
         //  gsm.welcomeMessage();
        //   Thread.sleep(1000);
         //  gsm.welcomeMessage();// for turning on Echo ATE1&W

           Thread.sleep(20000);

           gsm.hangup();
           Thread.sleep(1000);
           gsm.closePort();
           gsm.outCommand();
           System.exit(1);


         } catch (Exception e) {
           e.printStackTrace();
         }
       } else {
         System.out.println("Can't init this card");
       }
     }


    }

Edit:-

I have found way of auto answering the call by setting auto answer mode using AT commands after modem is initialized but it is not always reliable and for the purpose I am using the modem I need to get the timing right for playing audio clip the moment when Call is answered Audio Must be played .Auto answer using AT commands answers the call but the problem of playing audio remains.So I need some way of find how to detect Ring

Answer 1

I can't talk to the specific API or why you are not getting an event. However, your backup plan of parsing the inputStream looking for RING has a few potential issues.

The principal one is that your implementation is depending on RING being sent/read in the same read operation. There's no guarantee of that - it is quite possible, depending on implementation of the underlying API, that you end up with the stream one byte at a time (in which case you will get R I N G as separate strings).

My recommendation is to create a StringBuffer, append the StringBuffer as long as you have input, then check the StringBuffer.

Something like :

 case SerialPortEvent.DATA_AVAILABLE:

   StringBuffer sb = new StringBuffer();
   byte[] readBuffer = new byte[2048];
   try {
     while (inputStream.available() > 0) 
     {
       int numBytes = inputStream.read(readBuffer);
       sb.append(new String(readBuffer,0,numBytes));
       System.out.print(numBytes);
     }
     if((sb.toString()).contains("RING")){
        System.out.println("Enter Inside if RING Loop");    
        welcomeMessage();
     }
     //print response message
     System.out.print(sb.toString());
   } catch (IOException e) {
   }
   break;