This number 404-566-3810 called today April 23, 2015 at 10:31AM.
I did not answer they left this message.
The callers message stated "This is Christine Madison"
Please call 888-888-9355, use your number on the back of your card and reference the return "RETEN1".
The 888-888-9355 is a toll free number for a health care provider.
Their customer service has no information about this caller or call.

I had exactly the same experience as Omaha above.  no matter when you call that 404 number back, you get a recording that says youve reached Direct Energy (which has no office in GA, btw) , their hrs are 9 - 6 mon - fri and they are closed now (even if you are calling in that timeframe) and to call back then, but you will always get the same recording so go in circles. this is obviously a scam and perhaps that "retent" code triggers a virus, who knows. Today i got a call again but no msg left. Omaha, your post was helpful and I hav this # on call reject.

PS the first time I got the call where they left a msg, the caller had/used my full name. I coincidentally happen to be insured with that healthcare company, so now I am disturbed. I could not make out that code (reten1) on my vm so never gave it to the cust. svce. but there were no notes on my account anyway. be careful...it may trigger an eavesdropping device/virus and the scammers could overhear your health information, passwords, ss#'s and other info you give to the health company to verify your id.