Received call from 202-087-6556.  Caller ID was Washington DC.

Same here. Three rings then hung up.  What's with all these crazy calls?  Testing phones or something?  Weird.  I'm getting tired of phones and am considering just doing away with them entirely.  Too intrusive, especially with freaks like these.

I have a London, UK Skype number for my customers over there. When it rings here, Caller ID is showing the London number they are calling from, 20-xxxx-xxxx. Maybe it is someone with a Skype number configured wrong so it goes to you instead of them. No idea how you would fix that, except spend a few pence and call 011-44-20-xxxx-xxxx and ask them who they were trying to reach. Of course, the same thing could come from many other international countries as well. I just noticed your reference to the 202 area code and remember going through the same thing until I figured it out.