My only recommendation is to press *60 on your phone and add to Call Screening.   Good luck.

Unfortunately the 312-187-5581 could be a "spoof" number on the caller ID.    Next time you receive this call, immediately press *60 and try to add last caller to the "call screening list".    It might work.   Joe

This and several other similar 312, 708, 773 numbers calling me every day several times a day.  I asked several times to be put on their do not call list and they still keep calling.
This call is pertaining to your electric bill.
Recent changes allow you to save money on your electricity.
Press 3 to be taken off the energy saving program.
Press 5 to speak to an agent.