phone line RJ31X supervision versus rule to monitor fault/trouble

[rexwilson]

The M1 manual says that the RJ31X can be supervised by putting a resistor on the orange and blue terminals, then creating a trouble/tamper zone with those wires.
However the M1 rules also contain "Whenever Telephone Line Fault Trouble Is Detected Then".
If one is using the rule, is there any reason to also have the RJ31X be supervised? Is that overkill? Is there ever an occasion when the rule would trigger but the RJ31X supervisory zone would not, or vice versa?

 

[electron]

Interesting question, I have been having some issues with my RJ31X setup, didn't even think about monitoring it.

 

[Del91574]

Two different and entirely different applications.

The M1 looks for phone voltage. The orange/blue pair method only supervises if the RJ cord is plugged into an RJ jack or removed.

Usually I've seen the cord method used when there's another communications method and the installer wants to supervise the connection to the phone line for notification purposes and technically, per the FCC and tariff rules, the RJ is supposed to be left accessable without the need for tools or special knowledge, not within a locked cabinet. Other dealers do it to provide a false sense of security to some subscribers, a la, "we supervise your phone connection". The other reason is to maintain a system trouble which prevents the system from being armed or gets the subscriber to call the dealer for service if the alarm is unplugged by whoever, even just get it to be logged into the system. Lots of reasons why to do it.

The voltage method may or may not be worthwhile in a non-POTS application, as the VOIP ATA may or may not provide voltage depending on connectivity.

How it's implemented varies, as well as via rules.

 

[rexwilson]

DEL, that's very helpful, thanks.
Sounds like the M1 rule method would catch both a cut cord and a random voltage drop even in a physically intact cord, and that the orange/blue pair method would only catch the cord being unplugged (which would presumably also trigger a voltage drop). So if I'm not concerned about either the FCC or about a false sense of security to the subscriber, then I can have full coverage by simply using the rule.
If anybody can think of something I'm missing, comments would be appreciated. Thanks again for all your help

 

[Del91574]

Without arguing the FCC and entire items that come with it, the facts are that the telco needs free access to the 31X for troubleshooting purposes, not by opening a panel or similar, which is what the FCC tariff acts are. I haven't seen push come to shove too often, but by all rights the 31X is supposed to be left exposed outside of the can (though everyone else doesn't do such typically, as it's contrary to a security install). The telco can cut and disconnect all subscriber wiring on the customer side of the dmarc to provide functioning dial tone there, and the 31X allows easier troubleshooting for them to remove a possibly locked up dialer from the phone lines (not as common these days as the past).

The line cut may or may not be an option depending on the service in your area. I've had panels generate telco faults when the subscriber was on the phone for extended periods and the loop voltage for the phone line started to sag, so YMMV.

What the hardwired pair method does do is insure the cord remains plugged in or generate a system event (if voltage supervision isn't possible) or send a signal via a backup method. Does nothing else.