I keep getting a call from this number. I do not know who they are or what they want.  When I call back I get an automated voicemail.

File a complaint with the FCC.
Telemarketers cannot call cell phones, if you get one, file a complaint with the FCC.
Also, telemarketers cannot call after 10PM, if they do. File a complaint with the FCC.  I used to work at the FCC, and they do go after these telemarketers, but there has to be enough complaints filed. 100 complaints is enough to be referred to the Enforcement bureau for investigation, but a complaint has to be filed.  Go to http://esupport.fcc.gov/complaints.htm  and follow the prompts. Or call 1-888-225-5322 and ask to file a 1088 about telemarketers.

Update:

I tried to call them back but I received an error message: "The number you have dialed is no longer in service please check the number and dial again."

I have received 1 Phone call from this number... they are out of Atlanta Ga. They did not leave a message and I did not call back.

I got a call from that number and I didn't answer and there was no message

Called. no message.

called. left no message

Recieved call from this number....did not leave a message! I dont usually pick up nor call back the ones without voicemail....probably some stupid marketing call.

Called, I didn't answer and they left no message. I called back and it said that the number isn't in service.

Called, I didn't answer and they didn't leave a message.  When I called back it says the number is not in service. How does that work?

called, I didn't answer, no message, name shown: Throxus Marketing.

called, i didnt answer and they didnt leave a message

Called, didn't leave a message