sundance-communications.com/forum Forums TDM Business Telephone Systems Avaya - Lucent Telephones & Systems funny T-1 issues

I have a customer with a local T-1 from AT&T. On this T-1 are about 20 loop and ground start lines. Some of the lines are used for their main local incoming hunt group and some of the lines are assigned as principle users. Their are also other lines assigned to the 70 pool for dialing out. The problem is this: Every 3 to 4 days, my customer has to reset the switch because all the incoming local lines on the T-1 appear to be busy and the caller gets a busy signal. We know they aren't all tied up on actual phone calls because this has occured after hours as well, when no one is on site. It is like the trunks are getting seized for calls and not releasing. AT&T looked at it from their end one day and said all the trunks were seized. Once we do a hard reset, the problem goes away. We have swapped T-1 cards with no success. Disconnect supervision is set to yes, but I don't think that matters on T-1's anyway. Anybody got any ideas? I think it is with AT&T, but they claim otherwise. How can I test? Anything in maintenance where I can monitor a line?

Make sure line coding (AMI, B8ZS) and framing are same all the way from A.T.&T. to your switch. It may be an option set wrong at the local exchange carrier. Most of these T1's are multiplexed and demultiplexed several times before they get to the end user. If A.T.&T. is your provider they need to open a ticket with the local exchange carrier to have options checked. Also if this is a PRI check the D channel and make sure it is in service since your call setup for the rest of the trunks is done on this channel.

Local exchange carrier is transparent to line coding and framing format. It will be done at AT&T and the end user. Have them put up a trap to see what happens when it fails to release, they can tell you who is causing it. (at least they could when techs were doing it, management has taken this over now, so expertise may no longer be there)
Bill

Local Exchange Carrier should be transparent to end user but not the case. I worked for a major LEC for 30 years. We had to option our multiplexers based on word document from interexchange carrier. Many times options were set wrong in error or because circuit layout record was incorrect. This happens most often when circuit comes into LEC at the DS3 level and is demultiplexed down to the T1 level before dropping off to the end user.

If you can change all of your trunks to ground start - I believe you will take care of your problem. I had one years ago that some of the trunks were changed to loop start to due centrex service and I started having trunks being seized and the customer had to get the co to release the trunks or power down switch to release them.

We have verified the signalling is correct. According to AT&T, they see an off hook condition from out switch which is causing those trunks to busy out. Is there any kind of forced release I can program? All the trunks are loop start. I don't want to convert them to ground unless absolutely necessary to try to fix this. Any other ideas?

You need to look at the T1 signal from your switch with a test set capable of monitoring a T1 signal such as a TBird 207 or 209. These test sets can monitor individual channels of a T1 and verify busy or idle and the signalling states from both directions.

Stay on the path of reliable disconnect from the CO. Can they confirm the disconnect signal you are receiving? Without a T-berd its hard to say if you are receiving or sending an Idle condition of
A bit=0, B bit=1, C bit=0, D bit=1
You can trace the trunk in monitor and hang up on the far end to see if you receive the CO disconnect, it will say; REC true far-end release. Then try hanging up on your end it should say; SND true-disconnect. or something close to that. I'm getting old.

How can a trace the trunk? Is it trace 801??

Since each of the trunks has it's own individual number, I can call in on a designated line, but i want to make sure I am tracing it right.

Trace on 801, Trace off 801. You can type "status" to see what tracing you have on. Don't leave any on when you exit monitor.
Wax on Wax off