We have a Nortel Nortsar MICS using a PRI with 23 channels. Occasionaly (once a week) when someone tries to dial out to a local or long distance number they get a fast busy signal. Like wise when I have tried to dial in to either a DID number or the general company number I received a fast busy.
I have had the telco company check the line as well as the company that supports our phone system and no one has any idea.
What could be causing this?
Thanks
Ryan
Does this happen at very busy times? It seems possible (from the amount of information I have gleaned) that all the lines coming into the Norstar are full. Although now that I think of it, I'm not sure that would return a fast busy signal (I can't remember exactly what happened the last time we had full PRI blockage at this site).
Actually we have 12 employees and 23 lines so nealy impossible unless everyone was on the phone and receiving a call. I beleive we have 22 or 23 inbound line with the PRI, correct?
Thanks for your response.
Ryan
Yes, a PRI has 23 "B" (bearer) channels and 1 "D" (data) channel. It's possible, however improbable, that all the lines could be used. If you have 10 people making outbound calls, and 13 people trying to call in, leaving/checking voicemail, connecting to modems, sending faxes, etc, you could have some blockage there.
I would call telco and ask them for a traffic report on the circuit for a specific day that you know you experienced the issue. While this is likely not the cause with such a small (and probably over-trunked) office it may point you in the right direction.
I'll be interested to know what you find out!
~ Michael
Michael,
Thanks for your comments and concern. Our Nortel phone support company came out for a few hours this morning. Last night before I left I turned on the PC based syslog for our Adtran Atlas 550 that sits between the Nortel and the Telco. This morning when I came in not much info was revealed except for this attempt that was captured:
Sep 29 08:29:24 10.0.0.126 ATLAS 550[ADTRAN]:ISDN|Ntw2|1|Call to ATLAS:'719xxxx' received. Sep 29 08:29:24 10.0.0.126 ATLAS 550[ADTRAN]:ISDN|Ntw1|1|Dialing
719xxxx Sep 29 08:29:24 10.0.0.126 ATLAS 550[ADTRAN]:ISDN|Ntw1|1|Gate opened to name by Proceeding Msg. Sep 29 08:29:25 10.0.0.126 ATLAS 550[ADTRAN]:ISDN|Ntw1|1|Call clearing: UNASSIGNED_NUMBER : Loc=U Sep 29 08:29:25 10.0.0.126 ATLAS 550[ADTRAN]:ISDN|Ntw1|1|Call to '719xxxx' failed Sep 29 08:29:25 10.0.0.126 ATLAS 550[ADTRAN]:ISDN|Ntw2|1|Call to '719xxxx' busy after switchboard has connected it. Sep 29 08:29:25 10.0.0.126 ATLAS 550[ADTRAN]:ISDN|Ntw2|1|Busy destination: UNSPECIFIED_CAUSE : Loc=LN Sep 29 08:29:26 10.0.0.126 ATLAS 550[ADTRAN]:ISDN|Ntw2|1|Call to '719xxxx' disconnected by far end.Adtran tech support is sending a new chassis. No idea, but tomorrow the Nortel company is coming back to take the Adtran out of the loop (we will lose out fax machine for a few days) to see if we can isolate while we wait for the replacement chassis.
Will let you know what happens.
Ryan
Very interesting, thanks for the follow-up.
Because I was interested (and someone else reading this might be) here's the link to Adtran's product information page on the Atlas 550:
The Atlas 550 is amazing. I know it does many other things, but I use it to allow the break out the PRI into analog circuits. I have 16 analog ports on the 550 that I connect to analog modems to dial out at night when there is zero phone system traffic. It dynamically uses and release the 23 lines from the PRI that feed the Nortel phone system. It will also band together 2-4 T1s into a single channel for increased throughput (I believe). Pretty cool tool and there Tech support is better than Cisco!
Anyways, seems the problem is the 550 as we removed it while we waited for a replacement from Atlas and the problem has disappeared.
Thanks for the help.
Ryan
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