I answered with my normal greeting, and there was nothing on the other end. No sound, no person, nothing. I waited for a few seconds, and then the call ended. We've been getting a lot of these lately, it's rather annoying.
Advertising solicitations from Manta and/or Yelp. Constantly saying your Business information is incorrect and needs to be updated so "your customers" can find you. Just so happens for $600 they can fix it for you.