How to know whether I am in a call on Android?

You need broadcast receiver ...

In manifest declare broadcast receiver ...

<receiver android:name=".PhoneStateBroadcastReceiver">        <intent-filter>                <action android:name="android.intent.action.PHONE_STATE"/>             </intent-filter></receiver>

Also declare uses-permission ...

<uses-permission android:name="android.permission.READ_PHONE_STATE" />  

The broadcast receiver class ...

package x.y;import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.telephony.PhoneStateListener;import android.telephony.TelephonyManager;public class PhoneStateBroadcastReceiver extends BroadcastReceiver{    @Override    public void onReceive(Context context, Intent intent) {        TelephonyManager telephonyManager = (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);        telephonyManager.listen(new CustomPhoneStateListener(context), PhoneStateListener.LISTEN_CALL_STATE);    }}

And one class to customize phone state listener...

package x.y;import android.content.Context;import android.telephony.PhoneStateListener;import android.telephony.TelephonyManager;public class CustomPhoneStateListener extends PhoneStateListener {    //private static final String TAG = "PhoneStateChanged";    Context context; //Context to make Toast if required     public CustomPhoneStateListener(Context context) {        super();        this.context = context;    }    @Override    public void onCallStateChanged(int state, String incomingNumber) {        super.onCallStateChanged(state, incomingNumber);        switch (state) {        case TelephonyManager.CALL_STATE_IDLE:            //when Idle i.e no call            Toast.makeText(context, "Phone state Idle", Toast.LENGTH_LONG).show();            break;        case TelephonyManager.CALL_STATE_OFFHOOK:            //when Off hook i.e in call            //Make intent and start your service here            Toast.makeText(context, "Phone state Off hook", Toast.LENGTH_LONG).show();            break;        case TelephonyManager.CALL_STATE_RINGING:            //when Ringing            Toast.makeText(context, "Phone state Ringing", Toast.LENGTH_LONG).show();            break;        default:            break;        }    }}

TelephonyManager.getCallState() returns one of

• CALL_STATE_IDLE
• CALL_STATE_OFFHOOK
• CALL_STATE_RINGING

If this fits your requirements, it's much less code than Pied Piper's more comprehensive solution.

You can only come to know call is coming but you can't modify this. :(see this why 2.3 version of android does not hava android.permission.MODIFY_PHONE_STATE ? and what is the solution for this?