They called me last night when i was in a deep sleep and ended up keeping our line tied up all night on intercom/conference call.  WTF???????!!!!!!!  Have to pay $20 to my phone service to find out who these F#$%&Rs are!! UNACCEPTABLE!!!!

It doesn't really waste their time because these are almost always made via computer.  In some cases the call is only made to validate that it the number rings.  In other cases, the computer only sends a ring tone to the call center once someone answers the number - that's why there is often a delay when you answer these calls.

They are very efficient systems and you really aren't wasting their time - they're playing a game of odds and making hundreds of calls per day.

Hung up, left no message

I never answer the phone from unknown callers like this one! I just turn off my answering machine and let the phone ring and ring (ha, ha, to waste their time).

Caller ID says missed call w/out message from "Washington   DC"

Did not answer but have found no information for such a number online so I can ONLY assume it is just another spoofed number used by scammers and does not really exist.