This is a slamming attempt to get your to change your natural gas supplier, supposedly to save money (hah!).  If you give them your account number they can use it to switch providers.  You still get the bill from your local company because they own the pipes that deliver the gas to your home but will see a separate billing section from this company for the actual gas used.  You will pay a delivery to the local company as well.

THIS TIME THEY ACTUALLY KNEW MY "ADDRESS" AS WELL....I TOLD THEM THEY HAVE THE "WRONG NUMBER".

Watch out! This company seems to be cloaking itself. I did a search for 800 numbers
and found that 877-401-7959 is in the 800 number database at inter800.com. The only information
they show is "Energy -  Dallas, TX 75241"; no address, no phone number, no contact information.  Strange that a company in Dallas would identify itself as an Illinois company.  Ignore them.

This number always seems to call when I'm not home.  Leaves the EXACT same message every time, so obviously it's a recording of the same lady named "Kelly" requesting you to call her back "with your (gas) bill in hand.".  They must think some people are just stupid.

Got this call who is it

"Please call with your gas bill in hand." "Calling about our gas bill." Person says their name is "Kelly." Call almost every day at various times. Company they claim to be calling from does not exist in our state.

Appears as a missed call on my phone at work.

i have no idea who it was left no message when i answerd, call constantly

Call constantly