Area code 240
SW is reporting 240-754-2987:

Spoofed Numbers: Caution, 240-754-2987 is a "spoofed" number, which means that whoever called you "tricked" your caller ID to display an incorrect phone number.

Reported 22, Oct. 2014.
Oliver is reporting 240-215-3310:

Woohoo, I finally figured out a way to stop this persistent caller using multiple phone numbers (which actually helped me to find the solution). Call 866-246-7196 and give the caller's and receiving phone numbers. This phone number is on their list so they added my receiving phone number to the do not call list and the calls stopped within their 1-2 business days processing time.

Reported 22, Oct. 2014.
Anonymous is reporting 240-318-1607:

telemarketer--to be stopped!!

Reported 22, Oct. 2014.
Anonymous is reporting 240-252-5164:

Telemarketing about auto insurance coverage. Asked if you can save money, would you switch companies. It seemed weird since they were calling a business rather than residential number.

Reported 21, Oct. 2014.
Sandy is reporting 240-292-9156:

Robo calls from some company trying to sell Home Security.

Reported 19, Oct. 2014.
Anonymous is reporting 240-252-7124:

Message ask to log on to my carries website in which I had a credit. SCRAM

Reported 18, Oct. 2014.
GET EVEN is reporting 240-397-5331:

this bitch calls every day, several times a day, company Med Advance. I am sick of the phone companies ignoring this problem......they certainly CAN DO something to prevent this. We put this bitch through the steps expressing interest, allowing her to earn the pitiful minimum wage they're paying her and tie up her time, and then tell her to get lost.

Reported 17, Oct. 2014.
Smarter than that is reporting 240-252-4879:

I just got a call from 240-252-4879. The fool on the other end claimed to be from Microsoft Windows. I knew right away this was a bull shit call so I played along. He tried to tell that MS Windows (which BTW is an operating system not a business name or a call center) has detected malware on my hard drive and he was calling to offer me free assistance to remove it. I fucking hate assholes who try to play on my (so called) fears, greed or whatever.After he said he needed me to be in front of my computer so he can guide me so I can let him into my computer I said to him, "Well you're going to have to wait until I buy a computer then because I don't own a computer. ". He said, "You don't have a computer?" I said. "No there is not one computer in this house and if this was not a scam call you would have known that. I love messing with these idiots. LMAO

Reported 17, Oct. 2014.
Anonymous is reporting 240-397-1066:

Health care company - recorded call

Reported 16, Oct. 2014.
Anonymous is reporting 240-342-3341:

Dirt bag scammers that call weekly trying to steal information.

Reported 16, Oct. 2014.
Anonymous is reporting 240-670-4099:

Caller is an ESCO, making reference to my Con Edison account.

Reported 15, Oct. 2014.
Anonymous is reporting 240-724-1801:

Calls and hangs up

Reported 13, Oct. 2014.
Exchanges in the area code 240, Maryland