You need to have a timestamp from which you select the missed calls. Within the database there are three timestamps (at least for SMS) which should have more or less the same content. If you frequently miss calls you might try something fixed like "missed calls within the last 24 hours". Or you define a timestamp whenever you ask for missed calls and use this one as reference. I don't know whether it is possible to select exactly these entries that are displayed on screen. But there also has to be a timestamp for that.