Disconnect Timer 1

[jjimm]

I have a hung line on a 6.1 MICS ksu with Call Pilot 150 , which may be due to disconnect supervision. I have checked my trunk lines -
DS is set to Super
Full Autohold is set to N

I am calling telco, but have two questions-

Is there a "default" time on the LS/DS trunk cards in the for the OSI interval for the disconnect timer ?

Wouldn't briefly reversing the polarity of the line emulate the disconnect signal from the CO ? (after this I would change the line back to straight polarity)

 

[jerryreeve]

Just disconnecting the CO should clear a line that is having problems recognizing CO release. Definately make sure that you have disconnect supervision (or whatever your LEC calls it)on the lines though.

If voting could really change things, it would be illegal.

JerryReeve
Communications Systems Int'l
com-sys.com

 

[bkrike]

And yes there is an adjustable timer that you will want to match to whatever interval the CO is sending.

 

[jjimm]

Here is the result, for those that may need it in the future-

Shorting the line does not release the line, neither does disconnecting and reterminating it.

Reversing polarity released the line. Polarity was then restored to normal.

Default setting on LS/DS cards is 460 ms. The time should then be set to match the CO time for DS.

 

[hawks]

If disconnecting the system from the line did not hang it up Telco has a problem with the line not you. One thing you can do is call in on the line from a cell phone. Answer the line with one of the system phones. Then when you hang up the Cell phone within about 1 or 2 seconds you should see the line drop on your NORSTAR phone.

 

[galfaro]

I would try calling from a fax line instead of a cell phone. or any POTS line if available. Cell phones are so unpredictable.
Gabriel

 

[jerryreeve]

I am thinking that you are not seeing a hangup as the trunk is still showing active on the phone system (you are getting messages n VM saying "if you need to make a call please hangup....". Hawks is thinking that you are grabbing a line after the phone system shows the trunk clear and still being connected to the original call.

If my thought is correct then you probably have a problem with the LS/DS card and should try swapping it out. If Hawks is correct then his suggestion of the telco problem is also the way to go.

Disconnect supervision on the norstar is Open Switch Interval OSI and is set by default at 600MS not polarity reversal.

If voting could really change things, it would be illegal.

JerryReeve
Communications Systems Int'l
com-sys.com

 

[jjimm]

Just to reiterate- THE PROBLEM IS GONE.

The line was hung up.It got this way due to onsite user error. I released the line by temporarily reversing polarity on the line to emulate a CO disconnect signal. This was the only thing that worked.

After releasing the line I called telco to match their DS signal speed, which was 600 ms. Also re-checked KSU programming to make sure "Super" was on, and "Full Autohold" was set to no on the line(s).

Hopefully this info might help someone else in the future. Of course there are always other ways to approach a resolution.

Thanks to all for your help!

 

[trabra]

jjim:

In order for you to reverse the polarity you had to reverse your jumper and my guess is it was actually the temporary disconnect that released the line. I had a situation several months ago that played out on this forum as I fought SBC to prove that they were not sending a DS signal. After almost 3 weeks of joint dispatches and techs looking into the problem, it turned out to be an old SLC96 that had problems and 8 business lines had to be swapped to copper for the problem to go away. That one line being hung do to operator error is probably not a DS issue and if you had a DS issue the lines would hang, especially on the voicemail, anytime an external caller hangs up before the system drops the call. I'm including some verbage from Mike Sandman about DS or CPC (Calling Party Control) depending on what type CO Switch the LEC has and what the Switch manufacturer calls this parameter. I hope that this helps!

FROM MIKE SANDMAN'S WEB SITE:
CPC (Calling Party Control) is a signal sent from most modern electronic COs to indicate that the "Calling Party" has hung up. It's usually called "Open Loop Disconnect" when you're programming telephone equipment.

CPC is normally sent as an open ranging from 250 to 500 milliseconds. Phone equipment at the far end of the call sees this open on the line, and hangs up. Most voice mail and phone systems have a timer setting for CPC. If you set it at 500ms, it usually works fine. If you accidentally set it for 50ms you'll probably get cut-offs, especially during a lightning storm during very brief blips in the loop current. Setting this timer for 50ms means that if the phone equipment sees an open for 1/20th of a second (not very long), it will hang up. Setting it for 500ms means it will hang up if it sees an open of half a second. That's much more reliable.

It's pretty hard to measure CPC timing, but you can at least verify that there is some kind of CPC. Put a volt meter across the line and answer a call. When the calling party hangs up, you should see a blip on your meter. That's the CPC, but most meters can't respond fast enough to show you much of anything. An oscilloscope would show it to you, if you happen to have one around (and know hot to use it).

 

[jjimm]

Different resolutions work for different problems. For my problem, I waited a full 10 minutes after disconnecting and shorting the line. Nothing happened. The line was still hung up.
I reversed polarity by flipping the jumper and puched it down on the trunk port. the line imediately cleared.

I guess everyone could draw their own conclusions, but it seemed to me that it WAS the polarity reversal that did the trick.

 

[jerryreeve]

I can agree with you that from what you told us the polarity reversal probably did the trick but the confusion is that it probably shouldn't have so we are gonna wonder why or how.

interesting question was where was it hung up. in the phone system or from the phone company?

If voting could really change things, it would be illegal.

JerryReeve
Communications Systems Int'l
com-sys.com

 

[trabra]

jjimm:

Is this the only time that a line has not released and was hung? By the way, what did the user do that caused the line to hang up? That is very odd that you disconnect the line for 10 mins and the line didn't release. By chance, did you recyle the power before doing the line disconnect and polarity reversal? Just wondering if while the CO line was stuck if a power reset would have released the CO Line as well?

 

[jjimm]

There were two factors that caused this. My documentation from my last visit showed DS(Super) was turned on . Later I found out that someone had turned it off.
What caused this problem (I am told by the customer) is that someone plugged in a computer into the voice jack, taking a set out of the jack) to get a modem line.

My theory is the system interpreted this as a virtual set (the display read "284" in use) and allowed him to grab the next available line, which was this one.
He used it and then unplugged the computer without disconnecting the line first.

The other sets could not access this line- it was "in use" and could not be interrupted- they have autoprivacy on. Since the system was set to not use DS, it stayed on. Maybe it would have cleared automatically if I had turned the DS on first (since I believed it was already on, I didn't check until after I was done,and was updating my records), but I was curious, as well as anxious to get rid of the problem. I instructed the customer to use a fax jack next time they need a modem (since they didn't want me to install a new modem jack...)

Well, hopefully this answers any loose ends. My apologies for being so "sure" that DS was turned on. Just another example of when you ass-u-me.

Of course, the customer denies making any changes. (I wish I could talk to the guy that gave her the installer password so I could strangle him).