In a message dated 9/17/2002, Rob Keller writes:
> So, because of the ring signals, which would exceed the > limits of SELV, connecting to the input the modem, should the > classification be TNV-3. Hi Rob: If the tip/ring pair that the DSL modem interfaces to has power ringing on it (such as for an ADSL modem used on a standard POTS line), the classification would certainly be TNV-3. It really doesn't matter that the DSL modem does not use the ring signal. What matters is that the signal is present. Note that some DSL modems (HDSL, SHDSL) operate on lines that do not have power ringing. For these applications, the typical classification is TNV-1. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 http://www.randolph-telecom.com
