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

You've changed calling and called parameters if available? Guessing but in some manufacturers there are versions of unknown,national,subscriber,international,etc.
Check also to see if they updated the CO about the time the problem appeared. Have also seen the wrong trunk group keyed into a MAC at the CO on an unrelated customer cause this.

Since you've changed the PRI board with the same result I'd demand a joint vendor with their protocol analyzer as the customer and attorney are standing by.

Ed,
Not too long ago, we resolved a very similar symptom with a PRI: Luckily, it turned out to be something quite simple: Although most of our PRIs are "B8ZS/ESF", this specific PRI was initially requested to have the coding and framing set for AMI/SF, which we had done both here in the switch, as well as confirmed at the far end (terminated to a Siemens switch). However, our Mini-mux 840 that transported the PRI from here to the Siemens was still set at B8ZS/ESF. Our switch indicated the PRI as in-service (but with a local alarm on the DS1), and *all calls dropped after the first ring. As soon as we updated the setings on the Mini-mux to reflect AMI/SF, the alarm cleared, and calls processed fine.

I have to agree with gcave: Recent telco software change, causing a Q.931 protocol's call setup message data mismatch (in the 5E, we would receive "level 3 errors" when retrieving the PRI status).

BTW: What is the "caller" hearing after an inbound call is dropped? Are they receiving a recorded announcement, reorder tone, or silence?

Where are you directing the DID's too? Have you tried moving the DID to an extension another device? I have run into these issues a long time ago..luckilly the Tadiran diplays Q9.31 messenging so you could nip it in the butt. It's weird you can place calls and not recieve..that means the d-channel is up. You definately need to see what they are sending you. Possibly they are sending 7 digits?

Mike: What the caller hears depends on the type of line they are calling from. If calling from another PRI, just one cycle of ringback tone is heard, then the calling PRI is given the command to drop the connection. If calling from a POTS line, one cycle of ringback is heard, then a reorder tone is returned.

Coral: We have confirmed that they are sending us three digits, which is what we are looking for. We even set up a completely different switch and programmed routing tables to receive anything from 1-7 digits for just one particular DID number. No matter what, the result was the same thing as above.

I'll call a local contact [DMS100 Tech] to get his opinion for us. Like Anthony said, this may require Vodavi TierII speaking directly with Verizon TierII. PRI calls simply dropping after the first ring doesn't usually start happening "out of the blue"..I think that some type of software or translations change had to have occurred at Verizon's end. Make sure that you identify as closely as possible when this actually began happening.

Could there be a possible conflict with the PRI's BTN (billing telephone #?) The BTN has alot to do with the Q.931 setup message (i.e: if the BTN is no longer a valid TN, the setup message will prevent the PRI calls from processing due to a billing conflict.) That's why this puzzles me...the outbound calls process fine across the same PRI.

Mike that is possible but I would think they would get a direct reoreder not a partial ring. Wish we could get our hands on a d-channel trap, It would give us a lot more to go on.

Hey Ed,

Can you provide the entire set of "D" channel messages for the call reference of a disconnected call? I have my co-worker who would like to take a look at what you have.

Dexman.

I don't have anybody on-site now to capture a trace and since the PRI is my only way to get into the system's modem, I can't get one right now. All that I can remember was that the last line of trace information provided is that our switch receives a PRI clear request right before the call drops. From what I can tell, our switch is being told to drop the call, so it does.

Update: The customer got fed up when Verizon threw their hands up over the issue. They are having them bring in ten POTS lines to replace the PRI. That really stinks.