Just got a new phone number a week ago because of similar issues like this and this was the first number to start calling - won't leave a message and of course can't call back. Very frustrating. Why should we have to be subjected to these stupid calls EVERYDAY??? I am on the do not call list but don't think it has kicked in yet because it usually takes about 30 days so I hear. Number says it's out of LA so all I can assume is that it's a telemarketer.
As long as your phone # is registered with the "Do Not Call Registry", you can make a complaint about receiving calls from 213-504-7015. Go to this url: https://www.donotcall.gov/complaint/complaintcheck.aspx to register your complaint.
I have received 3 calls from this number and I just got a new number through Comcast less than a week ago. It comes up unknown and there is no message. I have registered with the do not call registry.com and added this number to my blocked numbers. 213 is in the L.A. area and it is one of four numbers calling my UNLISTED new number within the first 24 hours. Apparently Comcast is selling new numbers even though they charge to be UNLISTED!