How can Telephony.Sms.Conversations be used to retrieve convo information to String?

I tried:

ContentResolver cr = context.getContentResolver();
Cursor convo = cr.query(Telephony.Sms.Conversations.CONTENT_URI,
                        new String[] { Telephony.Sms.Conversations.ADDRESS,
                                       Telephony.Sms.Conversations.PERSON },
                        null,
                        null,
                        Telephony.Sms.Conversations.DEFAULT_SORT_ORDER);

How ever I get error invalid column address. when I remove address I get invalid column person. What column's does this class provide? (I couldn't find anything on the API reference page or any examples online. btw I already have a working code to retrieve inbox and outbox but I would like to get conversations too (I mean title and num of msges), without matching inbox and outbox results)