method or code in android to know if the call went to voicemail

What we can do is get when the phone is ringing and it is not answered, when you are dialing a number or when you cancel the call, and to get the number that sent the voice message you could use getVoiceMailNumber() of TelephonyManager (may not work for all providers)

This requires READ_PHONE_STATE permission in your manifest, as detailed by HERE

To implement the first and know when you miss a call, when it is ringing or when you are dialing we can do the following

We create a class that is a listener that listens when one of these things happens, called missed, call in progress, or answering a call

 int prev_state=0;


  public class CustomPhoneStateListener extends PhoneStateListener {  

        private static final String TAG = "CustomPhoneStateListener";  

        @Override  
        public void onCallStateChanged(int state, String incomingNumber){  

            if(incomingNumber!=null&&incomingNumber.length()>0) incoming_nr=incomingNumber;   

            switch(state){  
                case TelephonyManager.CALL_STATE_RINGING:  
                        Log.d(TAG, "CALL_STATE_RINGING");  
                        prev_state=state;  
                        break;  
                case TelephonyManager.CALL_STATE_OFFHOOK:  
                Log.d(TAG, "CALL_STATE_OFFHOOK");  
                prev_state=state;  
                break;  
                case TelephonyManager.CALL_STATE_IDLE:  
                    Log.d(TAG, "CALL_STATE_IDLE==>"+incoming_nr);  
                    NumberDatabase database=new NumberDatabase(mContext);  
                    if((prev_state==TelephonyManager.CALL_STATE_OFFHOOK)){  
                        prev_state=state;  
                        //Llamada contestada que termino
                    }  
                    if((prev_state==TelephonyManager.CALL_STATE_RINGING)){  
                        prev_state=state;  
                        //Llamada cancelada o perdida  
                    }  
                    break;  

            }  
        }  
    }  

  

CALL_STATE_RINGING

Called when the phone is ringing

  

CALL_STATE_OFFHOOK

It is called when we are dialing some number

  

CALL_STATE_IDLE

Called when a call is rejected or not answered

Then you must make a class that extends to BrodcastReceiver to get this data with a method onReceive()

public class IncomingBroadcastReceiver extends BroadcastReceiver {

@Override
public void onReceive(Context context, Intent intent) {

 TelephonyManager telephony = (TelephonyManager)context.getSystemService(Context.TELEPHONY_SERVICE); //TelephonyManager objecto 
        CustomPhoneStateListener customPhoneListener = new CustomPhoneStateListener();  
        telephony.listen(customPhoneListener, PhoneStateListener.LISTEN_CALL_STATE);          //Registramos nuestro listener con TelephonyManager  

        Bundle bundle = intent.getExtras();  
        String phoneNr= bundle.getString("incoming_number");  

        mContext=context; 

}

I hope you serve