You will be happy to know that you can report unwanted telemarketing cellphone callers at:
http://www.fcc.gov/complaints. I'd use the ".gov" rather than companies advertising to give this service.
If these alternate energy suppliers get you name from a utility company, they are not violating the Do Not Call List. Companies that you have done business with in the past are exempt. So since almost everyone has electricity, this is one way of getting around the DNC list. I used to work for one of these suppliers and as a Rep, we were prohibited from telemarketing but the owners of the company setup a call center using numbers from the utility companies. Now, they have started using numbers out of the "White Pages". This is a violation, that is why I am a former employee.
Ever received a call to "lower your interest rate". Well your credit card company has sold your information.
I would still report them, it is worth a try. Each State is different but most have a department that controls public utilities, it may be worth a try to file a complaint with them.
Just because you have a business relationship with your local electric company does not mean it is legal under the DNC regs for alternative energy suppliers to contact you to try and get you to switch to them. If you contact your electric company you will find they have not provided your contact information to the alternate energy suppliers. Why would they want you to switch to another supplier? It is especially illegal to call random numbers such as cell phones that are not in any way associated with your electricity account. If this caller was legit, they would already have your account info including billing name, address and account number as provided by your electric company. If they do not, it is an illegal telemarketing call and you should report them to the FTC and FCC and possibly your State Attorney General.
Called my cell phone, first time I ever saw the number, so I denied the call, it left a six second voicemail containing beeps and blips, sounded a bit like a fax machine. No harm no foul I guess, as long as they don't call repeatedly.