PRI Lost Calls

[Arr]

I've got a 16 channel PRI on an unexpanded MICS that seemingly at random presents a 'no answer' condition to a caller. This is an extremely busy PRI handling a lot of very short inbound calls on one target number.

The installed line up is MICS Rls 5.0, 1 T1 Card, 1 CLID card, 1 6pt Combo clock card, 1 CP150, 12 Sets, 1 SMDR6, 2 Konex ATAs.

CP150 answers only two target lines with AA. No CC at this time.

We are able to see the 'no answer' call on the SMDR6 inbound from the target line, but the call doesn't show ringing on a station. There are several sets programmed to ring on that target line with 5 intercom keys each. There is no prime set configured for the target line.

Actions to date: upgraded from 4.1 to 5.0 replaced pri card (because it was easy) Checked programming against carrier, run carrier logs, checked internal channel setup (near & provisioning) and checked Dchannels and event/alarm logs for hints.

Can't seem to find a pattern in any one thing.

Carrier stated that our KSU wasn't sending the connect signal back to them. Also stated they see no clocking slips. But we see the call comming in on the SMDR but not landing on any of the sets.

Anyone have a suggestion? Hate to change out the whole cabinet and find the problem continues.

Cheers
PhM

VVV

 

[senk1s]

- Does the SMDR give the physical trunk (1-23) the call is coming in on?
- If any, What are the other 7 channels used for?
- What protocol are you using on PRI

- If the trunks 1-23 are primed to a set - do the calls come there

 

[Arr]

Senk1s,

SMDR reports target line and trunk. Trunk variously reported at 2 or 3. All 16 channels are open to any of the DID/assigned numbers.
PRI protocols are B8ZS, DMS100, ESF, CSU (both on and off tried) currently off, Clock source Primary, and Bchannel sequence is opposite telco all has been triple checked against the carrier (not that that means everything).

When the target line is primed to a set it made no difference to the situation. Removed prime as a last effort to corral this.

PhM


VVV

 

[senk1s]

the remaining chanels are they used for Internet access?
Are they dynamically allocated ... if so i'd get that changed and reserve 16 and only 16 for voice

I was asking about the primeset on the lines itself (not target lines) - that'll work even when the recd # is not accurate.

Did you try NI2?
Did you turn on ISDN Cause codes and look at them?

 

[Arr]

Senk1s,

All 16 channels dynamic voice only. No partitions.

Prime set for lines is 221 and 221 is set to ring on effected target lines.

Didn't try NI2 have not had good experience with NI2 and Norstar. Could do though. Thoughts on that?

ISDN cause codes. Turn on? Went back to the KSU and don't see that as a discrete heading in this 5.0. What have I missed?

Event and alarm codes all match shut downs, changes and interuptions that the Carrier and I have caused. No surprises.

Thanks for your replies.

PhM


VVV

 

[bigcat919]

On most, if not all MICS's I've worked on were set for NI-2. Almost all problems with NI-2 have been with the carrier. NI-2 should work pretty good. Suggest you check with the carrier and make sure your line one is their line one. Had one account where the carrier's channel one was the system's channel 23. If the incoming calls are trying to come in on a busy channel...therefore no answer. Food for thought.

 

[Deweyhumbolt]

All my Norstars and BCMs except two, use NI2. Those two use DMS100. I'd leave internal CSU on.

Stupid question, but are callers complaining of RNA or are the SMDR reports the only symptom. Callers could be hanging up?

Adversity is Opportunity

 

[jerryreeve]

Can you go back into your smdr data and verify that all 16 channels have been receiving calls, I am wondering about channel 16 specifically. I have seen some confusion when a T1 is reduced in channels like this that the data channel (that stays on channel 24) is counted as one of the 16 by the customer (you) but not counted as one by the telco, when the telco presents a call to the system by data presented from channel 24 (D Channel) for a channel that you have not programmed for use at your end, you do not acknowledge the call and the telco drops it.

you may need to monitor with a firebird and see what the data is that is presented to you from the telco on the dropped calls. what channel is attempted etc.

----------------------------
JerryReeve
Communication Systems Int'l
com-sys.com

 

[Deweyhumbolt]

So Telco doesn't laugh at you, it's called a Tberd.

Adversity is Opportunity

 

[jerryreeve]

Ya I think firebird was a specific manufacturer a while back.




----------------------------
JerryReeve
Communication Systems Int'l
com-sys.com

 

[gforce9]

You may have a DS1 issue, but you would see stuff in the 'Network Event Log' if this were so. A T-Berd would catch a DS1 issue, but not (necessarily)a DS0 or (for sure not)q.931 issue. If the Network Event Log is clear, you will need to find someone who has a tester and can decipher q.931. Telco can look at these messages, but rarely explain them or cooperate with you on them.

 

[Arr]

Bigcat919,
Lines match.

Deweyhumbolt,
Callers complain of RNA, SMDR reports RNA at the caller specified times and staff are really good at answering all the ringing calls. I've stood in the CC while watching an RNA call on the SMDR and no ringing on the floor. Spooky. So callers not haning up.

JerryReeve,
No confusion on PRI. 16 B channels PLUS D. Calls landing properly in sequence L1, L2, L3 etc, outgoing picking L16, L15, L14 etc.
Event codes that correspond to my meddling are
EVT 337-252 S3
ALM 44-0
EVT 372-00 S4
EVT 336-00
ALM 75

Sequence repeats as shut downs and upgrades procede.

I could insist carrier come in with a TBerd. I could log into the pair-gain box. But since these calls can be seen on the SMDR my first thoughts are that the calls are being lost to a programming error.

Perhaps we'll try NI2 change first.

Cheers
PhM


VVV

 

[jerryreeve]

you might try creating a hunt group for the target line with the members having appear/ring of the hunt group. and remove the target line appearances from the individual stations. with the hunt group in broadcast mode for distribution of the calls.

reason I am suggesting this is that it effectively changes almost all of the programming for the target line appearances. as well as that you get some reporting of dropped calls etc under programming.

----------------------------
JerryReeve
Communication Systems Int'l
com-sys.com

 

[DMWSr]

Just a wild stab - but do you have anything in the Business Name field (in System Programming)? We've seen this mess things up as some carriers are not equipped to handle this data from the phone system. Not really a critical field to have programmed so you should leave it blank.

 

[RikRodgers]

One thing that hasn't been mentioned here yet is the sw revision. Anything before 6.1MR had target line issues, and I've had trouble with dropped calls right up to 7.1, though all my PRI's with 7.1 sw are running fine.

Just to note, all my sites are running NI2, but for the telcos in this area, that's their standard format.

 

[Arr]

Thanks all for the continued suggestions.

Tried Hunt groups earlier. No change and no additional info.

Don't have a company name set up.

Coudn't get the carrier to call back today so no NI2 changes. Going to have span outed and re written from scratch.

Cheers
PhM


VVV