I'm re-routing and adding some phone jacks in the house and found an oddity.
Originally, the line came from the telco side of the demarc box over to my side and was screwed down onto two terminals (red/green). The two cables that feed the outlets in the house were tied down to these terminals as well (white/blue pairs).
It appears that when the alarm system was installed, the installer lifted the original cables and ran a new cable from the telco box to the alarm control panel. The telco screw downs are tied to his cable (white/blue) only and the pair goes straight down to the alarm box. It comes out of the alarm box on his (white/orange) second pair back to the telco box and is spliced to my original cables' (white/blue) pair. I'm guessing that if/when the alarm box grabs the line on the inbound pair, it has the outbound pair open so another phone can't come off hook.
If found the installation manual on the alarm box and what was done is exactly "per the book". It tells the installer that the alarm system should have the "first" shot at the phone line and that nothing should be between the alarm box's connection and the telco interface. No way to fault the installer, but I do have a couple of concerns.
Since the alarm was installed, we have added DSL. And in case anyone is particularly knowledgeable, the alarm box is a DSC PC1555.
The alarm guy's wiring is not CAT5, it's CAT3 or some other kind of station wire and because of the routing, the circuit runs through it and the alarm box before coming back to the telco box where it's spliced to my inside wiring. That's adding about 100' of lesser quality cable before I ever have a chance to get it to my modem.
The DSL signals are high frequency, so that "noise" is getting shot straight into the alarm box and I see no kind of filter outside the box and no reference in the box's manual about it having any kind of high frequency filter.
Occasionally, we have problems with the DSL and I wonder if the alarm box occasionally grabs the line to report in or just test itself. There's no sort of filter around the alarm box for this either. If the alarm box comes off hook, it has to "look" like a telephone and therefore it's presenting a
600 ohm load to the line across the entire frequency band. It think that this is what the the "store-bought" DSL filters are supposed to prevent. Maybe this is happening and causing out intermittent "outages". If the alarm box is grabbing the line and doing what I suspect, then the house outlets are effectively "dead" when it happens.Has anyone else ran into this before and did it cause any problems?
My first thought is to tap the alarm guy's cable and grab what is effectively the "first" presence of the telco pair inside the house to run my additional outlets and put the appropriate DSL filters on the new drops that I run. Secondly, I'd like to find out if there is any need for some other kind of high frequency filter between the line and the alarm box.
TIA-trebor