It is Just Energy. They are a Natural Gas supplier. There are mainly two reasons as to why they're calling you.
1.) They want to be your gas supplier thru Consumers Energy, keep in mind that they give you a fixed rate with a 5 yr plan. However they raise your fixed rate by $1+ every year. And there's a cancellation fee should you decide you no longer want them as your Gas supplier. Out of all the Natural Gas suppliers to CE Just Energy is the worst.
2.) Perhaps you signed a contract with them thru your apartment complex or thru you current landlord/landlady and they want to confirm your name, or perhaps you just recently moved and they're trying to track you down to see if you'd still be interested in receiving their "fixed rate" on Natural Gas.
Just Energy and other Natural Gas Suppliers are not scams they are legit business that supply gas to Consumers Energy and DTE, despite the common belief that CE is in control of the gas and electricity that they provide to the public they are in fact Not. They are supplied the Gas thru companies such as Just Energy.
You can look up the Gas Choice Program on Consumer Energy's website for more info. However, out of all the Natural Gas Suppliers Just Energy is the worst.
-Note- Unless the name of the Gas Supplier is on Consumers Energy's website in the Gas Choice Program section Do Not agree to the terms. Unfortunately for those of us that work for Natural Gas suppliers, scammers take a lot of our business and as such we are meant with hostility and anger when wanting to save you money and become your gas supplier.
Gas Suppliers all have fixed rates and they keep you at that fixed rate for 12 months never raising your gas price even in the winter time when gas prices sky rocket, there by we're saving you a ton of money through out the year.
Unfortunately Just Energy like to takes advantage of your generosity in letting them be your gas supplier and unlike the other suppliers they raise your prices.