Caller ID says Circulation. Get a call a few times a week from this number. Most of the time the call disconnects at the same moment I pick up the phone but today there was a woman with a thick accent who asked for our technical proposals manager.  I'm sure it's to "renew" his "free magazine subscription" as we get those types of calls constantly.  Once I can determine the nature of these calls, I make a note of the Caller ID and next time they call I simply pick up the line and put them on hold. They eventually hang up. It doesn't stop the calls but at least I don't need to talk to them.