I have received multiple calls from 301-553-1434, caller ID "WALDORF    MD".  My answering machine has picked up the line, but the caller leaves no message.  There are a few scam reports for this number on other web sites.

2/19 - this number (301-553-1434) keeps calling from maryland. they have called 5 times between 9:30 am and 12:30 pm. This is the Window technical support scam. I asked them to quit calling here and they hang up but this last time I told them to never call here again and the man on the other end with an Indian accent called me a f***ing idiot.

this # 301-553-1434 calls everyday 4 or 5 times a day between 8:30 am to 12:30 pm, nobody answers but you can hear an office type sound in the background, tried calling back and was told not a working number.

As JD said above, this is the Windows Technical Support scam, apparently trying to gain remote access to your computer.  In the past, I have always told them that I didn't have a computer and they never called back, although one did argue with me and accuse me of lying.  But this particular one is relentless.  The first time they called (today at 2:00 pm), I told the guy with an Indian accent that I didn't have a computer and he hung up on me before I had the chance to tell him off.  I immediately blocked the number and just looked back at the caller id to find that they have called six more times since then and it's just now 4:30.   In fact, they just called again while I was typing this.

None...