Will an Answering Machine cause the D168A not to answer when accessed locally?
Some answering machines load down the phone line and cause it to go below 7 VDC. The D168A needs at least 7 VDC to properly process the DTMF tones.
Can zones 7 and 8 be used as normally open zones, and do they require any supervision?
Zones 7and 8 are not supervised on the D2112 and D2212 panels and therefore can only be used as normally closed zones, they will not work as normally open zones because no EOL is used. Voltages of 2.4 to 13.9VDC would be an open condition while voltages 0.0 to 1.4VDC would indicate a closed circuit on these points.