DID intermitten problem

[sromero]

I have a Norstar 0x32 in one of my remote sites and over the last three weeks we have experienced intermittent busy condition on all DID calls. I don't believe the trouble has lasted more than 30 minutes before it clears.
I've had our service provider test the PRI T1 and of course it test clean, I've also had our equipment vendor dispatched on-site but again NTF.
The T1 is configured for 12 channels in-bound and 12 channels out-bound, the problem is only with the DID's the outbound is not affected.
Just wondering if anyone has experienced something similar and what was the outcome of the problem.

 

[cowenby]

How long has the PRI been in service?

MICS?

What version software is in the system?

Is it possible there are 12 incoming calls when busy occurs?

Try changing your limits back to the default settings:
Min in:0
Max in:23
Min out:0
Max out:23

Setting limits to 12 in & 12 out defeats one of the great advantages of PRI, diversity factor.

As a last resort, you may want to connect an SMDR and a printer to look at traffic when this is happening.

Best of luck on resolving this problem...

 

[sromero]

Thank you cowenby for your reply and advice!

Great idea! connecting a printer to look at the traffic.

The PRI has been in service for 3 years, never experienced any problems until recently.

Yes it is possible that all 12 DID trunks could be busy, however, during the times of trouble I've talked to the receptionist and each time she indicates light usage 3 to 4 people on the phone.

I let you know when and if I find a resolution.

 

[cowenby]

Also, look at the destination code for the outgoing line pool. If it is "9", change it to "9 Any". I know this sounds strange, but in some cases a caller who dials "9", gets interrupted and doesn't complete dialing or release the call before timeout can lock up a channel. This happens more often than you might think and the problem may not become apparent until periods of peak traffic. It may be possible that this could reduce your DID capacity. We experienced busy signals on DID numbers with no calls connected, before the dest code was changed from "9" to "9 Any". I believe this issue may have been fixed in the latest MICS 6.1 Maintenance Release WI 6.05 that was released in March 2004.

This points up the biggest headache with PRI. When it works, which is most of the time, it works very very well. When it doesn't, it can be a pain to troubleshoot and isolate the problem. In our case, the PRI was installed in March. We started noticing problems in April that continued until November. After seven months of intermittent outages (failure to process calls), several hundred manhours of troubleshooting and testing, replacement of the core cabinet and all cards, and two visits by factory engineers; the problem was finally resolved by changing the dest code from "9" to "9 Any". It's worked like a charm for the past five months.

Hope this helps...

 

[senk1s]

i have a MICS4.1 with PRI ...with rel 1 NVRAM ... and this was one of the problems ...well not exactly ...

but they cannot make outgoing calls, if they get an incoming call then it starts working fine ...no alarms or anything. this system was also working fine for about 4 years and hte problem started a few months ago ... NT said change the NVRAM card ...

 

[jerryreeve]

I'm confused, I have set up T-1`'s with DID and Outgoing service but when you set up a PRI it goes to Call By Call. Is this Channelized T-1 or t-1 PRI? also have you looked at the error logs?


JerryReeve
Communications Systems Int'l
com-sys.com

 

[sromero]

Hey guys, thanks for all the good tips!
So far the problem has not resurfaced, but it bugs me not knowing what caused it in the first place.
I don't know how I got into the PRI mentality but the T1 is channelized. 12 outbound ground start and 12 DID E&M wink.
The software release is 1/T1

 

[cowenby]

Don't worry, most bad bugs that go away unexpectedly, usually return equally as unexpectedly, and usually at the worst possible moment.

With regard to my comments; they only apply to an ISDN-PRI.

Good luck!

 

[jerryreeve]

You may also want to see if your LEC can give you a busy study on the T-1, it would tell you if people are getting busy's and when. you could have the study done several weeks in a row and hope to catch the problem. it's not a fast troubleshooting tool but it can help sometimes.

JerryReeve
Communications Systems Int'l
com-sys.com