This number called, didn't answer. No voice messages. I have been receiving a LOT of calls like these from the Washington State area. Who are they?

caller id says L7 Srvc Call.

Home security scam. They are also using 253 763-9468.

Called the other day under 253-753-9458 L7 SRVC CALL, called 3 times today under 303-990-5754 same L7 SRVC CALL.  I never answer, and they never leave a message. You would think if your selling something you would leave a message and if that party was interested they would call back. The Do Not Call list does not help for some reason. Maybe because my number was given to a company I know and they sell it for profit. All those little fine lines.  Maybe the FCC should start going after the companies selling the information to these 3rd party individuals, maybe then it will stop. Some people posted under the other number Debt Collector maybe if they left messages they would collect the debt.