Caller ID says cellular call.  A person not speaking very good english identifing himself from yellow pages.

Answer and no one there - no message left.

A man with broken English calls for some "Yellow Pages" that you cannot understand and then wants to verify and find out your company information.  This is where I turn into an airhead and act like I don't know anything about the company I work for and then hang up.  You can tell it is a scammer calling.

A man with broken English calls for some "Yellow Pages" that you cannot understand and then wants to verify and find out your company information. I called number back and got a recording "this  number is no longer in service"

Answered the phone, got the 5 second "dead air" silence (which automatically lets you know it's a telemarketer).  Wait for the caller to respond in broken English and they want to "confirm" information about my business.  I always tell them that they have reached a field office for the IRS and that we will be happy to assist them as soon as they answer a few questions ...they always hang up at that point.

I've started using telemarketers as stress relief:
Ask them what they're wearing, then tell them you're naked.
Tell them your returning their call.
Ask them what they want on their pizza.
Repeat everything they say to you in even MORE broken English.
Babble non stop about how your day is going, then start screaming!