atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems A simple ground start line...

Or so I thought.

I was dispatched out to a city PSAP today for a line out of service. I arrived to find that another tech was out yesterday and proved the dial tone to the demark and went above and beyond to trace it out to another building until it disappeared into the ceiling. He advised the IT dude to call his vendor since there was a bunch of extensions out on the console and there was no clear place to terminate the line on his equipment. The vendor came out and said not my problem, need dial tone to this block on my system and it will work.
I retrace everything and find it going to a disconnected phone system in another building so I removed that jumper, then traced it into the PSAP and to a cut 25 pr cable up in the ceiling. We go back to the room where the vendor's equipment is and the customer says that another line that appears on the console is working, he calls it and low and behold the relays start clicking and the light lights up on the old ktu, and sure enough there are the extensions that are out.

Since I was getting the "you really need to fix this for me" look from IT dude I placed a temp. bypassing the old ktu and they are now able to receive calls, but can't dial out due to
the line being ground start and their equipment isn't set up for it. I also advised them they need to work with their vendor in getting all their other lines off of the old 1a2 since it's not really needed.

Now for the question, was I just being sent on a wild goose chase or are there 2wire ksu boards? My best guess is the number had was somehow connected (i couldnt find it) into the ktu and they vendor then wired the extensions off the 1a2 into his system as c.o. Lines. Is that possible? Sorry for the long story, but it had and still has be baffled, and I dont like that!

It happens all the time. The syndrome is called "1A2 system as IDF"

In big buildings where the old original Bell stuff is abandoned in place, (in a main shaft on the floor) the interconnect installer just picks up the dial tones off one of the 25-pair station cables, to feed the new KSU generally located inside the customer's space.

Then, years later, somebody scrounging for old 1A2 stuff pulls out a 400D card, the line goes dead, and everybody is confused.

Rather than bridging the T/R which wouldn't care if the 400x card was there or not, it was connected to the T1/R1 which the card uses with the A-lead control.

But using ground start lines on a 1A2? My only experience with that was when the key set was behind a PBX with one line looped through a normally closed relay with the key set having a ground start button on the face plate. That way, it was essentially a power failure line.

Thanks for the replies Authur and Dave.

I've worked for a LEC for 11 years now and this is the first time I've ran into a 1a2 system still in service and will admit to not knowing a thing about them and told the customer I wouldn't touch it out of fear of taking down the other lines.

It was definitely a ground start and as far as I could tell it wasn't wired into the 1a2, but the extensions that were down are and those extensions were associated with the ground start line. I should have walked away, but it was obvious his vendor wasn't going to help. I guess if the original vendor did the install correct, this would have been a non-issue