Three rings

Lately we’ve been letting the phone ring during dinner time, since usually these calls are from telemarketers. We noticed that most of the ignored calls terminate after three rings, even though our machine waits for four or five rings before picking up. Theory: telemarketers hang up after three rings. If true, I’m happy to wait until the fourth to pick up. But why would telemarketers hang up after three? According to this article at www.stretcher.com (scroll down to Third Ring Response), the auto-dialers hang up after three rings to avoid paying for a connections to answering machines. Right on!