Hi Sparrow!

Gee, I thought DB was going to explain what a squelch circuit was, but he didn't. :-(

Sorry I didn't say more about it. This type of circuit basically cuts off transmission when there is no signal present. It's used, for example, in some radio transmitters to keep from transmitting low-level noise constantly. Low-level noise constantly being transmitted is extremely annoying to people who are otherwise occupied, for example a pilot flying a plane. Whether or not there are squelch circuits in phone switching networks, repeaters, 911 call centers, or in the Ramseys' phone I have no idea, but it could also save money and energy. Although I've never looked, speakerphones almost certainly have some circuit like this in the mic circuit that cuts the talker's voice off and annoys the listener, as I'm sure you've experienced. The beginnings of sentences can be cut off due to delay of reactivating the transmission once the talker's voice crosses a threshold volume.

Yes, someone certainly could have been monitoring the phones. DB mentions that the only advantage is a few minutes notification. No, that's not the case for all theories of what the crime is all about nor for all possible perpetrators. Yes, that is the case for certain theories and perpetrators. The advantage depends upon the theory of the crime and the characteristics of the perpetrator. He may, for example, have been a kidnapper who was half-expecting John to discreetly call one of his FBI friends. In that case, he wouldn't necessarily have known unless he was monitoring the phones. But it's good to see that Don is consistently objecting to this idea! He's obviously awake and paying attention. (Hi there Don.)