Received a call from this number, person claimed to be from Dell Computers.  Told them why does caller ID not say Dell Computer or Dell Inc -- hung up

Calls 4-5 times a day. Never leaves a message and if I do answer, it's machine that say "this is an important call for...." Never actually says a name. I'm not about to sit on hold for a machine. You called me a$$h@!e.