These people call several times a day and hang up when the call is answered. Its become incredibly annoying. Now when they call I just pick up the phone and hang it right back up. The called ID says Quinstreet. I googled this company and its a online marketing and media.

call several times a day. when picked up no one will answer the "Hello". sick of calls

Called repeatedly, at various intervals/days.  Don't recognize number, so didn't answer (they have gotten soooo sophisticated, with names that will make you react). Never a message.