It's definitely the Lyric Opera of Chicago. Those of us receiving calls have more than likely purchased season or individual tickets in the past. They are persistent!
Yes, definitely it is the Lyric Opera calling. Believe it or not, they are always in need of money, their costs exceed the ticket price. I know that's hard to believe, but nonetheless, true. So, the volunteers are busy manning the phones--don't be too harsh on them.
I say if you don't recognize the number calling you, you should not respond to their sales pitch but rather call the Lyric Opera on a valid number and follow instructions given by the valid number on how to buy tickets, if you want to buy tickets. Otherwise, ignore/reject incoming alleged-to-be-Lyric-Opera calls because it may be a scammer calling to steal your ticket money. It's much safer for you to call and buy directly from the LO.