Maybe not a scam... Received a letter at my business about a month ago regarding the Core Aggregation and Transportation Program (CAT), more commonly referred to as "Customer Choice." The number on the letter (855-CALI-GAS aka 855-255-4427) leads to a call center. They also followed up with a call to my business yesterday, trying to get me to sign up over the phone. I requested more info be sent to me via email, but have not received anything yet. At this point, I don't know if this particular company is legit, but the program they are selling is approved by the PUC. Basically, you sign up to purchase your gas direct from a third party supplier to the Gas utility at a (presumably) lower rate than the utility charges. The Gas Company still delivers your gas, services your account and bills you. I'm still doing research, but you can find more info if you search online for "Customer Choice Gas Company" or similar search terms.

these clowns (Customer Choice Center) keeps leaving voicemails at our answering service.  SPAM garbage re: gas bill.

left message about discount on gas bill i called back and they were legit I've saved about $300 so far and ive only been enrolled for about 4months

But left message to call back at (855) 225-4427 - re gas bill discount.

Left message saying they could discount our gas bill.  Probably a scam.