If you didn't answer the phone, then how do you know that it was a telemarketer? The Caller ID states "UNAVAILABLE." Your presumption may or may not be correct.
3/25 10:30 PDT Person claiming to be offering A/C and Heating maintenance. Don't know why I answered, but told the person on the other end that I already have a maintenance contract with someone else, he politely said "thank you" and hung up. We'll see if this is sufficient.