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T1 card causing freezing

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lanstein

MIS
Jul 31, 2004
70
US
Hi everyone.. I have a 6.1 MICS with 2 DTI cards. We have 2 full T1s (B8ZS/ESF) with DIDs (no PRI). We are using the internal CSU on the cards. All of our calls come across the T1s.

Periodically, the entire system will lock up. It seems to happen when it is busy (although I'm somewhat relying on the unreliable receptionist to try to find the pattern). It has happened 5 or 6 times in the month since we brought the system online - always during business hours. I programmed a spare set with the first channels of the first T1 (incoming descending) and the last channels of the last one (outgoing ascending) so if the switch freezes again I can see how many lines were being used at the time of the freeze.

Both DTI cards have all of the error lights lit when the system freezes. I press the reset buttons on the DTI cards and allow them to fail out, then press the button again. All of the phones flash as if they were just plugged in and then everything works fine.

The alarm code on my set is usually 44-0. Essentially the only explanation in the manual is "T1 problem" which I could have determined in my sleep. I tend to think it is a telco issue and not a bad card since both cards have the error lights on. I asked the telco to test the lines and both them and Verizon (the telco rents VZ lines) claim to have them built to spec.

Since it seems to only happen when it is very busy, I am wondering if something is causing corrupt data to build up somewhere and that once it reaches a critical mass it locks up the system. I called my vendor and he seems to think it is a telco issue also. The tech support at the telco isn't what it might be so I'm hoping I can kick them into doing what needs to be done if anyone has any ideas.

Thanks for any insight.
 
Do you have enough DTMF receivers to handle the call volume?
 
When you are running 2 T1 cards it is recommended that you have 2 service cartridges or combo cards to handle the load. I have seen this problem and adding a service or combo will help.

Richard S. McCranie
CoMatrix Southeast
richm@comatrix.com
 
I do remember getting an alarm code 63 which is the no DTMF receivers available code, but I think I got it while the T1 cards were in the process of coming back up. Although if this were the issue maybe it didn't display because it locked up as the call came in. I'll check that if we have another freeze. Since we have the lines set up as E&M, I don't know how I would add more DTMF receivers...
 
aha, hawks you may have it:

"In a fully expanded system using 72 digital channels, consider installing two service cartridges to prevent blocking of incoming calls due to lack of DTMF resources, as there are only four DTMF tone receivers per cartridge."

So if I'm reading that correctly, if there are 9 simulatenous unanswered incoming calls, the system will lock up?

If I need a service cartridge, can I put this in the trunk mod since I don't have any more slots in the KSU?
 
The service card goes into a expansion slot. If you have depending on you config you will either need a combo card which has 6 ports for expansion and a service cart built into it.

Richard S. McCranie
CoMatrix Southeast
richm@comatrix.com
 
Okay so I can use slot 1 on the KSU? I have a combo card in slot 2 and the T1 cards in slots 3 and 4.
 
To save money you dont need another combo card unless you pan on expansion. All you need to get additional resources is get a service cart. That should take care of you problem.

Richard S. McCranie
CoMatrix Southeast
richm@comatrix.com
 
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