Hey, Arthur: I must respectfully disagree, or at least ask for clarification. You certainly have more experience than I do with this stuff.
If an RJ12C is T/R/A/A1 AHEAD of the line card (supposedly to keep ringer load on the line side of it) and an RJ13C is T/R/A/A1 BEHIND the line card for non-ringing devices, like credit card terminals, etc....Wouldn't what you said be contradictory?
Not to mention that a fully-protected line card (e.g: ITT K400-TPL) wouldn't even allow ring voltage to pass to the station side.
As long as anything sharing that line has properly-functioning A leads, I can't see false hold condition being possible.
THIS and
THIS are about the only things left that truly address these conditions anymore. In doing a Google search, it is very disturbing to me how many "authorities" give grossly-incorrect RJ information.
