atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's PRI problem; I am running out of options

I have a customer with a PRI that has completely failed, last Friday morning. Calls go out just fine, but ANY incoming calls provide one ring and then are dropped. Our trace on the system shows that a clear request is being sent by the serving CO switch (Verizon with a DMS-100).

Here's a little history:

The customer had their PRI from XO Communications for about two years, but it went down as frequently as three times per day. XO and Verizon could not ever figure out what was happening, so the customer just lived with rebooting the system. It usually came back up after that.

They eventually got fed up and switched to Verizon. Since both telcos are using a DMS switch, we didn't have to do much of anything except to move the cable from one smart jack to the other. It worked fine for a month without interruptions whatsoever.

Friday, they called us reporting that even a reboot wasn't doing the trick. We sent out a technician, armed with a replacement PRI card, among several other cards just in case. Nothing worked, so he referred this matter to Verizon. Since the customer had already opened up a ticket for this, Verizon was on the ready. They showed up, connected a T-Bert and came up with, well you already know what their answer was.

We spent all day Saturday taking another system over there and connecting it directly to the circuit where it enters the building in the basement. Same exact thing; works fine for outgoing; incoming results in one ring and then the call drops.

Today, I had two technicians out there to brainstorm and had Verizon back out twice. Same results. All new hardware, yet still the same canned answer from Verizon.

The customer was in the process of arranging to have a "fake" POTS line assigned to be used as a fallback in the case that the PRI failed. They did this because of the years of problems they had with intermittent outages. Although Verizon was charging them for a POTS line, it didn't really exist. It was just an alternate resource they would have available for emergency redirecting of calls. This just got completed recently, and my guess would be sometime late Thursday.

So now, as it sits, the customer has all of their inbound traffic directed to a cell phone where messages are taken. Employees then call the person right back. Verizon refuses to do much of anything else, except to keep coming out and showing us that their tester says, well again you know what they said. They claim that they can't escalate this because with it being a holiday, they don't have any higher-eschelon people to dig further. The customer is back in business tomorrow morning and their system still isn't working.

Even the same Verizon tech has indicated that all he can do is confirm the integrity of the pipe. He can't force anyone's hand since he shows that the circuit terminates proplerly. He does agree that someone messed up with the translations in the DMS, but only off-record.

They are a very long-term customer and I begged them not to go back to Verizon. They went against my advice and did it anyway. I doubt that they will jump ship and take their business to another vendor, but I do feel as if I owe them some kind of an explanation as to why this is happening.

The system is a Vodavi DVX+3 using 3.11 software. Like I said, it was humming along fine and then just stopped. Even with a complete equipment change-out, nothing has changed. I need help from you guys familiar with the DMS who can chime in with a donation of ammunition so that I can fire back at them.

Oh, and yes, Verizon claims that they ran a D channel trap, but our switch clearly shows a disconnect request being received from the CO every time a call is presented. They aren't seeing this, if the trap was actually run at all.

Hep me please, hep me!

Ed I think you've nailed it, sounds like either translations got messed up or D channel failing. I would think if it were the T-1 itself you'd have trouble bothways, maybe not the exact same trouble but some kind of trouble. Now the only problem is if they are testing the circuit D4 or just monitoring they may not see the problem on a SF T-1, the LEC's are bad about that.

Hey Ed see if you can get verizon to provide you with a copy of that trap. I agree it is not a pipe problem, A protocol analzer at the site is the only true way I see Verizon proving out this ckt. The t-bert will prove the loop, big deal, we know it is up, you are making outbound calls on it. Unfortualtley without being able to see the trap their is not much more I can suggest, maybe 5etek-Mike or Dexman has some input

Hey Ed.

You might try renting a TPI 570 Pri tester. This can monitor and terminate a PRI and can be rented fairly cheap.

This will give you a D Channel trap as well.

Being a DMS tech at a previous job is sounds that they do not have the number tables routed properly.

I would have them terminate to a Tberd and make incoming and outgoing calls this should prove it is there problem. The Tberd will let you make calls but the capture feature is less than desired.

Agree with Anthony..a protocol analyzer is necessary. Good luck finding one available in their system. Even SBC..sorry the new at&t had only limited access available for the entire local area code. Then when it got to site they had to find a craftsman that could operate it. A TBerd is only going to show pipe integrity not protocol issues. If an outbound call will establish and run for the duration then there is definitely a translation issue in their CO. ALLN1 probably has nailed the diagnosis as it looks like a breakdown in the numbers/group routing table. The only way I can get SBC/at&t to budge off center is to threaten to file an "executive complaint" to the president. They then run through their ass trying to do what they were supposed to do in the first place.

Had the same issue on a data T1 last year- Incoming packets dropping like crazy with nothing but a laptop connected to a brand new modem right out of the box. Turned out to be a provisioning issue on the telco side that was only resolved (after 4 hours) by being lucky enough to talk to the right support engineer at the telco who didn't have a preconceived notion that all his customers were clueless. Hang in there.

Just FYI.

There is a Tberd that will terminate, place and recieve calls if it has the option installed.

I personally have used the 2209 and the 224 to do this. The are great for placing calls and recieving calls but lacks in capturing D Channel signalling. Very difficult to decode. The TPI 570 will do this much better and easier. Also can be printed to a terminal emulation program for sending to the telco.

Have your tried to change your signalling to NI-2? It sound like the carrier is not sending the right ISDN Q.931 and or a protocol mismatch. Have them come with there T-BERD.

a fireberd is the way to go, but like RBF said they are few and far between and require a quilified tech. Swapping protocol just as a test is not a bad Idea, I have seen ckts function, poorly, but still function with a mismatch. I would also file the executive complaint, light a fire under their a$$ and hopefully get a tier 2 or 3 tech involved. Though you may want to be prepared, if you do get tier 3 involved they will probally want Voadavi tier 2 support on the line as well.

We can't change protocol with this system, so we really don't have a choice. It's fixed at NI-1 for BRI and NI-2 for PRI. Verizon swears that's how their end of the circuit is configured. OUr only options are the CO switch type, and dialing plan. We have tried variations of all parameters but all that does is affect our outward dialing capability.