Random digit dialing (RDD) is a method for selecting people for involvement in telephone statistical surveys by generating telephone numbers at random. Random digit dialing has the advantage that it includes unlisted numbers that would be missed if the numbers were selected from a phone book.
random digit dialing перевод:выборка, сделанная на основе набора телефонных номеров; распространенная техника построения выборки на основе телефонного опроса.