I have just this minute had 1 of those calls telling me i had completed a survey. I have told them i dont do survey nor do i want sles calls to which they hung up!!
There's a site that deals with this sort of calling, put the number in and it's likely to be able to give you the low down on whoever it is. whocallsme.com/
register with Telephone Preference, its free and stops all uninvited cold calls... especially those annoying ones where sales people call several numbers at once and you pick up and all you get is a silence.