How to add new field(s) and records to the call logs(call history) database?

Question

I am trying to make a VoIP application and I wanted to know if it is possible to do the following with the Call Logs content provider -

1. I want to add new Call L

Answer 1

Regarding the first question, you can use this code to add new records to the existing Call logs content provider:

public static void insertPlaceholderCall(ContentResolver contentResolver, String number){
    ContentValues values = new ContentValues();
    values.put(CallLog.Calls.NUMBER, number);
    values.put(CallLog.Calls.DATE, System.currentTimeMillis());
    values.put(CallLog.Calls.DURATION, 0);
    values.put(CallLog.Calls.TYPE, CallLog.Calls.OUTGOING_TYPE);
    values.put(CallLog.Calls.NEW, 1);
    values.put(CallLog.Calls.CACHED_NAME, "");
    values.put(CallLog.Calls.CACHED_NUMBER_TYPE, 0);
    values.put(CallLog.Calls.CACHED_NUMBER_LABEL, "");
    Log.d(TAG, "Inserting call log placeholder for " + number);
    contentResolver.insert(CallLog.Calls.CONTENT_URI, values);
}

(Code taken from Google Voice Callback for Android)

Remember to add the permissions in the Manifest

Regarding the customization of the call logs database, I do not think is possible.