You know why they dial up and hang-up before they talk to people? they are telemarketers paid by a publishing company to solicit subscribers for there technical or whatever magazine they have which are paid by advertisers. So, the telemarketer is trying to show they contacted umpteen customers so they can be paid accordingly by the publisher without putting the effort into it!
I've continued to get calls from this number. Every time I call back, it's a busy signal. Just for grins I called 1-312-878-5651 and an automated response says that the number I called will be removed from their system after 48 hours. We shall see.
This company calls but usually hangs up as soon as I answer. If I call back, I either get a message or am disconnected. One time I answered, someone said they were with a subscription center to a magazine I used to get but no longer want. I asked them to take me off the list, to no avail. Now they are calling at random times, possibly to annoy or harass.
I have file a complaint about this number to www.DoNotCall.gov