atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's T1 voltage out of SmartJack?

If there is a regen (Repeater) on the circuit, the active side will be in the CSR to CO direction. This assumes a T1 NIU that wold be span powered from the same repeater. Of possibly HDSL.

Most tech's change out a component, and when it restores, leave without any further analysis. Unfortunately a good number of Telco tech's do not look at the performance monitoring data that has been collected on both T1 NIU-PM units, or, on HDSL equipment.

At a minimum there are seven days of PM data, plus the current 24 hour period, available to analyze. This would help determine if there were incoming T1 circuit errors based on BPV line (CV-L) or CRC6 path (CV-P) errors.

The key is being able to detect error conditions, especially those that may be transient in nature. The D channe log is helpful from the PBX end, but knowing if there is an inbound trouble helps focus resources. The LEC switch shold havethe capability to monitor the D channel status. Not very fancy, but the camp on monitor available to the %e does help. Now the task si to get the LEC to turn on the D channel monitor at the switch. Or at best, place a protoco analyzer at the CO switch DSX-1 and monitor/trap D channel messages.

If you can get them, LEC, to recognize that a trouble exists on their side ofthe NI, the circuits may get fixed.

Good luck.

Field OPS

Good luck.

James -
What's the distance between the smart jack, the CSU and your box? What kind of cables? I ran into some weird issues that seemed like timing, but turned out to be cable length, posted here:
https://www.sundance-communications.com/forum/ultimatebb.php?/ubb/get_topic/f/17/t/000208.html

I've got issues with Airespring not publishing the right routing information, but never had any issues with dropped calls. The people who can't call us say they get busies, (some report fast and some report slow) or operator intercepts. Airespring pins it on us to tell them which carriers can't call us, but that's an impossible task, of course.

Cable length from Smart Jack to Box is about 25'.

XO replaced the repeater on the line and I've been running fine since. Not 100% sure why a repeated would cause the D-Channel to hang-up either. I guess if things are working then i'm content in not knowing why, atleast this time.

I'm still getting BPV's on the line but I just haven't been in that area to reset the card and reterminate the cable.

Remember what the guy said about memory in telco smartjack. 1 week/24 hr summarys. I used to work on the cable lines outside. A quick fix was to re-seat the T1 card. If it took too many errors its buffer would fill and start dropping.Some I was back the next day or week, and others never(bad telco line or bad seat in box) . If its the D all calls would drop. Do all active callers get dropped at once? As for incoming, If it is PRI you could have colliding B channels(busy or mis-directed calls). Your switch should be on DESEND, b8zs, and have the same number of B channels turned up as telco. They will be ACSEND.(handing out B's) Calls come in on 1 out on 23, unless 2 try at once to get 1 or 23. Otherwise report to serving telco- this number cannot call your number. You need example. and make trouble report to ask for un-intrusive monitor if established calls drop. I've seen bad repeaters too.

PS-voltage in to smartjack can be 130v to ground-voltage out you may see nothing or a very small ,like 2 volts to ground. You'll think your meter is broke. Its never been of any value to find trouble to me. They become transmit and receive pairs.

Kumba:

Ifthe LEC replaced a T1 Regen, more than likely if that did clear your trouble, it is an indication of a possible fault condition in the LEC's receive into the switch. Unless a protocol analyzer were placed on the PRI circuit to monitor Q.931 call set up protocol messages between your switch, and the LEC (Call failures or link SABM message), you will more than likely not see any T1 PM events on your end.


NDT4U:

Beginning in December 1989, the FCC under part 68 ruled that LEC's (Telco) will not span power customer T1 CSU equipment from the T1 span line. The exception to this rule applies to those T1's in place prior to the FCC rule change. ANSI T1.403 incorporates this requirement.

All new T1 NIU's deployed in Bell Atlantic as of 1998, now Verizon, do not pass any t1 span voltages to the customer side of the T1 NIU. If a T1 NIU installed at your location has a DB9 serial connector, and is made by ADA, Teltrend, or Westell, then thatis a NIU.

Units made by Pairgain/ADC, and Adtran are not NIU's but HDSL Remote units or HTU-R's. Older 4W (Gray color) Adtran HTU-R remotes have a slide switch to provide T1 span power towards the CPE.

I had the span powering option removed from all new vintage T1 NIU's, and HDSL HTU-R modules deployed by Bell Atlantic/Verizon beginning in 1998 & 2000 when I was a member of the Transmission Engineering staff.


Field Ops