Been getting a lot of these phone calls from the 240 area code, but with random (and non-existent/invalid) phone exchanges like this.  Also had calls from 240-132-4021, 240-180-3743.  Every time no message was left (aside from four seconds of silence on their end), so they clearly need to speak with a real person to unleash their con.  Weeks earlier, these same callers had previously attempted to reach me multiple times from "unknown" numbers, which are auto-rejected.  Same thing: four seconds of silence left on the voicemail.  I don't need any more free cruises or debt relief or back tax forgiveness or whatever, I'm already set for life.  So there. :^p