I check these guys out to see who they are then add them to my call reject list on my phone. They quickly go away. Check you phone to see if you have a Reject List.
Unsolicited and unknown number called my cell phone. All of my home/cell numbers are on the DO NOT CALL registry. In addition, phone numbers are "unlisted" so how they obtained my number is not clear.
No messages or voicemails but it is annoying nevertheless.