An excellent way to establish both the name and title of the Hiring Manager is the Mailing List Update Technique. Simply call the company switchboard (press "0" if you get an automated attendant) and say:
"Hi, I am updating my mailing list. Are you still at 123 North Main Street? And your zip code is still 54321? And what is the name of the manager of your _____ department? Could you please spell it? And what is her title? And does she have a direct extension? Thank you for your time."
If the switchboard operator asks, "Who is calling?" just give your name and nothing else. If the operator asks, "What is this in reference to?" or "What is this information for?" you should respond, "I am updating my mailing list for sending correspondence to this person and I would like to make sure the name and spelling are correct."
About 50 percent of the time this simple approach will get you all the basic information you need. But you will also find some professional screeners out there who will make their best effort to keep you from "stealing the company secrets." So if the Mailing List Update Technique doesn't work for you, read on.