How to make a phone call in android and come back to my activity when the call is done?

use a PhoneStateListener to see when the call is ended. you will most likely need to trigger the listener actions to wait for a the call to start (wait until changed from PHONE_STATE_OFFHOOK to PHONE_STATE_IDLE again) and then write some code to bring your app back up on the IDLE state.

you may need to run the listener in a service to ensure it stays up and your app is restarted. some example code:

EndCallListener callListener = new EndCallListener();
TelephonyManager mTM = (TelephonyManager)this.getSystemService(Context.TELEPHONY_SERVICE);
mTM.listen(callListener, PhoneStateListener.LISTEN_CALL_STATE);

Listener definition:

private class EndCallListener extends PhoneStateListener {
    @Override
    public void onCallStateChanged(int state, String incomingNumber) {
        if(TelephonyManager.CALL_STATE_RINGING == state) {
            Log.i(LOG_TAG, "RINGING, number: " + incomingNumber);
        }
        if(TelephonyManager.CALL_STATE_OFFHOOK == state) {
            //wait for phone to go offhook (probably set a boolean flag) so you know your app initiated the call.
            Log.i(LOG_TAG, "OFFHOOK");
        }
        if(TelephonyManager.CALL_STATE_IDLE == state) {
            //when this state occurs, and your flag is set, restart your app
            Log.i(LOG_TAG, "IDLE");
        }
    }
}

In your Manifest.xml file add the following permission:

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