atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Security, Alarms and Paging Fire panel and POTS trouble

Hello folks, I would like to pick your brain about some phone line issues on a fire panel at a school. Have no idea what brand it is becasue I'm just a lowly telco tech. The customer kept reporting issues on Line 2, but all my tests indicate no trouble on the line. So we reversed the L1 and L2 at the demarc. The next day they are reporting trouble on L1 which is the same telephone number that was feeding L2 the day before. I have changed pairs on my end and rebonded every splice I can find. The alarm guys have changed parts including dialers to no avail. I have verified this number is not shared by any other CPE. Anyone have a suggestion on what to do next. Don't know much about the fire alarm industry, but I was wondering if a dedicated fire line receives a call, does it go into trouble mode even if no one answers it? Since this is a new business I'm wondering if the number assigned belonged to someone else and people keep trying to call it?

who is providing the DT ?

have you looked at loop current ?

It is AT&T local. I have 23ma of loop current

I doubt it is because the call is not being answered. I know that you said you have verified that there is no CPE shared on the line, but are you really sure of this? The only guaranteed way to provide this is with an RJ31X jack. I'm not doubting your intelligence, but every (I mean every) time I've encountered this, we have found some bootleg connection somewhere. When it goes off-hook to use the line, the alarm system detects this as a line trouble since it isn't officially on the output side of the alarm dialer.

I chased one of these for two months at a high school. We eventually determined that there was a multiple of the F2 count that appeared at an outbuilding on the property. Yep, that same pair was appearing on an unused jack there and someone was using it as their fax line. They thought they were getting free dial tone. Since it was bridged ahead of the alarm dialer, each time the line was seized by the rouge fax, the alarm system detected the line voltage drop as a fault and reported it accordingly.

In your case, an F2 issue isn't likely, but have you physically verified that nobody has tapped this line up in the ceiling somewhere? Don't ask anyone to give you a truthful answer since they probably won't tell or they just don't know.

Oh, and

We aren't as dumb as we look!

Sorry Ed, but I just can't resist - those pretty pink fax machines have always given me the most problems too. But to your credit, those ugly beige rogue ones can be difficult to find.

The panel is fed by a 4pr Cat5e that runs 40ft from the demarc to the panel and every inch of the wire run is visible. I tested the OSP side and looked for foreign ringers and bridged tap and there is none. I am almost convinced this place is built on an ancient indian burial ground or something. As a tech it is getting hard to face this customer because I'm pretty sure they have lost faith in my ability and won't believe anything I say.

whats the loop current on the line that works ?

have you tried putting the problem line on a different pair ?

I would also compare polarity with the line thats working

The voice grade parameters are exactly the saem as the other fire panel line that never shows trouble. I have changed F2 pairs 4 times, F1 pairs 4 times, changed pair gain cards in the RT and CO, and we even ran a #4 ground wire into 4 manholes and I bonded the cable sheath and splice case to the ground wire. Polarity has been checked. All POTS at this address show 23-26ma.

Hello,
What type of switch is this being serviced out of? Is it coming off of a remote terminal? Have you replaced the line card supplying dial tone? I have seen bad line cards from an RT cause this, the card just dumps dt for a few minutes then comes back up. Maybe have your switch tech move it to a new oe???

...or have them replace L1 with a ul certified cellular dialer :rolleyes: