atcomsystems.ca/forum Forums Other TDM Phone Systems Vertical Telephones & Systems Won't release line on 2 incoming dial tones

Bill, they are not experiencing any crosstalk so could it still be split tips? I have run into this before with Cox sip to pots lines and my suggestions seemed to do the trick.

Yes, but I'm only talking POTS, if there cable company or SIP than my theory is out the window. You would get Xtalk if both lines were in use at the same time. He stated with butt set he could hear line go back to DT, yet he could also hear auto attendant, again if I'm reading what's being said correctly. Only takes a couple minutes to either prove or disprove this.

I read in the OP's post "Disconnect the phone system and call into the line and it drops and goes to dial tone as soon as the call is ended by the caller"

If an abandoned call returns dial tone, then loop supervision doesn't appear to be present.

Bill, I agree with you about disconnect (loop) supervision being a line group issue in the traditional sense, but telcos (if there is such a thing any more), often use pair gain hardware to extend lines to the premise. If these pair gain devices are not set to mimic the disconnect supervision via open loop, the line won't ever drop. Sure, you'll hear the click of the signal being sent by the CO when monitoring with a butt set, but that doesn't necessarily mean that the loop at the far end is actually being opened. The only way to test for this is to monitor the line's voltage when the click is heard. If it doesn't drop to zero volts for 600 milliseconds, then it isn't being repeated.

The "split tips" theory could be a logical answer as well, especially if pair gain equipment is in use. Crosstalk won't be prevalent if there is a short loop length to the SLIC, etc. that is providing the lines. Hey, there might be a pair gain cabinet at the nearest street corner, just a few hundred feet away.

Still, why did this just start happening? My guess is that the original installer of the system might have split tips when making modular plug connections to the system. The only true test of the split tip theory is to perform all testing right at the telco's demarc with a meter.

I'll bet a dollar that the plug for lines 3/4 has the tip for line one on pin 4 of the plug and tip for line 2 is on pin 1. The Summit uses pins 1/2 for line one and pins 4/5 for line two on an 8P8C plug (strange, but true).

Line 3 tip: Pin 1
Line 3 Ring: Pin 2

Line 4 tip: Pin 5
Line 4 ring: Pin 4

If the tips are transposed on these plugs, neither of the lines will truly go open upon receipt of an open loop disconnect signal.

Wow, this is some awesome information, I'm getting quite an education... now if I could just get my head around some of it.

They are POTS lines so Bill your theory is alive and well. Now to figure out what is going on. Interesting input also by Ed as far as to the proper wiring pin outs of those lines.

So here is what I am getting, and this sounds like what I should check/test

1) Check that the connector carrying those two lines is actually wired as Ed states (good possibility they were crossed and thus causing this issue, the way they were wired has remained constant through all this so a good possibility). I did notice that the connection was wired 1,2,4,5 but haven't traced those down to ensure they stay in the right sequence. I will make a note of your tip/ring values and check it.

2) If it is wired in correct order/sequence, then I will disconnect one line and test the other, then swap and see what the results are.

3) Still having trouble I will disconnect both lines, place my meter on it, and watch the voltage as the line is hung up on from the caller side.

If NONE of that shows as faulty, then my plan is to run screaming from the building and request an exorcism?!?!?!

This place is a bit outside of town, so there is a possibility of something added to boost some lines, although the CenturyLink guy informed me that all the wires are done up exactly like every other. But the input above gives me some good tests to perform and try to pin down the real culprit.

Thanks guys! This forum is great!

UPDATE:

Wiring doesn't seem to make a difference. However, I did put a meter on the lines with the following results:

All lines are @36-38VDC on hook, and 8.8 off.
Caller hangs up on good line voltage drop is to about 1VDC
Caller hangs up on problem line voltage drop is nothing on one of the lines, and to about 8.1 on another (did see it drop to about 4VDC once but usually still up close to 8)

Looks like it is a CO issue. Have a call in to see if this makes some headway

If anyone has some feedback/suggestions I am all ears. This place just wants their phones to work as expected. They are also still waiting to verify it isn't phone system before paying installer his balance. From these results does anyone think it could be possible in ANY way to be the system rather than the lines?

Just want to get some input as to whether I should tell client to pay, our issue is with CO. Just as a side note, problem is new because lines are new, old lines were either bundled on T1 or some other source. I think installer recommended they be taken back to POTS, not sure of rationale but that is what I have determined in my troubleshooting.

Greg

P.S. These problems are ONLY on incoming calls handled by the system. If office personnel call OUT on the line then things work as expected.

It's not the system. If it were, then the problem would follow the port, not the line.

Thanks, that was my thinking, just good to hear other thoughts.

"P.S. These problems are ONLY on incoming calls handled by the system. If office personnel call OUT on the line then things work as expected."

Greg, that's because the physical handling of a call by a human ensures that the loop current flow is broken upon completion of the call by the simple hanging up. It is the automated answering by systems that aren't able to determine when the caller is finished that demands that the disconnect supervision signal be sent. They never noticed this before because they probably didn't have an auto attendant on their original system.

Your tests further prove that the fault lies with the telco. I remember jokes about US West being referred to as "US Worst". I can't imagine that they are any better now after having been absorbed by CenturyLink.

The loop voltage must drop below one volt in order for ANY system to detect an abandoned call. Your measurements of up to 8 volts will never allow the system to operate under specifications as mandated by the FCC.

It's funny how manufacturers of systems are mandated to adhere to these specifications, yet the telcos that these mandates that are supposedly there to protect are the ones ignoring these very standards of service.

Since you're still seeing 8 volts even when the disconnect signal is being sent, then you really aren't receiving it. That's just your nominal off-hook voltage. I am still on-deck with Bill's theory of split pairs somewhere, and since there's no crosstalk between the lines, the split must be nearby.

But... I see improperly-provisioned line cards in pair gain cabinets responsible for not repeating the open loop signal almost daily. It's one of the two. It's just a matter of getting someone from 'US Worst' to verify this.

I will tell you that on-line trouble reporting with telcos seems to work better than actually talking with a live person in New Delhi. At least you can put information in the comments section that will potentially be viewed by someone with a pulse. Maybe you can copy/paste the information here in their comment section if it will fit. I found this out at my home a while back when GTE's CO wasn't sending disconnect signal. The technician in the CO who took the ticket read it, understood what was happening and called me to apologize for their ignorance. He never got it right (outgoing calls never received it), but at least incoming calls did, and that resolved most of my problem. I gave up the fight after that.

The programming changes I suggested will cause the line to disconnect if you are using an auto attendant to answer the calls. It is only a work around so you should pursue the telco to fix this issue at the same time.

I was given the login information by the installer when I was first called into this location. If you can give me an idea of WHERE those settings reside I will make a change. Spent lots of time on phone with telco today trying to get someone to listen. Person who I dealt with on-site is still telling me that he doesn't think the lack of voltage drop is what the problem is, but I think I've exhausted every other possibility. If it were the system then the problem would change with the port change and NOT stay with those particular lines/numbers.

Thanks for all your advice, phones are much more stable since I had the telco move these bothersome lines to the end of the hunt group, at least they get incoming calls MUCH less frequently and thus don't have to deal with this problem too often daily anymore. Still needs to be resolved though.

Greg