Samsung IDCS 100 with T1.
Users could not make outgoing calls.
All of the phones were up and working.
Called the T1 vendor and had them check the T1. They said the T1 tested good and it must be the phone system. I had the customer reboot the phone system. When the phone switch came back up the phones startd to ring constantly. When they tried to answer the calls no one was there. This went on for what seemed like 5 minutes. Eventually it stopped and the system seemed to process calls normally. I had to reboot this system once before and it did the same thing.
I checked the system alarm report and noticed alot of alarms on the slot the T1 is installed in. Alarms included sync failure, Blue alarm which says that the T1 is transmitting all ones.
Has anyone on here seen this problem before. If so, is it a T1 problem from the provider or would it be the phone switch. Any help or ideas would be greatly appreciated.

The ringing is the VM. Just press the answer release key and it will stop. It may also be the T1 alarm letting you know it's faulting.

As for the T1 sending all ones that is a problem. The only suggestion I have if you dont have one in place now is put a csu between the T1 and the system. That may solve your issues

on a T1 delivering loop start lines digitally, an all ones condition will cause all of those loop start lines to ring.

On that type of circuit, setting a channel to all ones is the signal to make that channel ring.

Pete is right. I was only thinking of the sync failure. But the exception to that is the T1 does not come up right away. It takes a minute or two and during that time it is not able to ring the phones

Thanks for the replys. The nonstop ghost ringing after reboot sounds alot like what Pete says is happening. I think I'll start with the T vendor and have them do some testing on that T. Would the T vendor be the one that installs a csu?

If they dont have one there then you will need to get one and install it

Usually the phone system vendor supplies any needed CSU/DSU, some phone systems have them built into the T1 card in the system.

Ok lets recap What exactly does the display say when the system "rings for five minutes"?

your answer here_____________________

Do you know or can you see if there is a CSU on the wall in the telecom closet?


your answer here_____________________

When was the last time a CLEC or LEC listened to what you had to say?

Your answer here_____________________

Condition the line with a CSU as was stated before. Check it again after clearing all alarms. Is there still a sync issue? How exactly is your T1 provisioned? have you been in system programming? This is about to go much deaper than this open forum will allow.

A line coding mismatch can occur anywhere in the digital network, from the curb SLC to your phone company switches and carrier trunking to a CLEC to your ISP. It is not uncommon for line coding errors to result from improper mis-match of the settings for AMI/B8ZS somewhere in the chain! Line coding errors may go undetected by the phone company or its customers, and test equipment and techniques commonly used to check and troubleshoot these systems may fail to indicate any problem!

So how was the t1 configured again?

There is no CSU. I have been in programming. The T1 is configured for B8ZS. I cantacted the carrier when the T went down. They did some testing and said that everything looked fine. I monitored the system all day yesterday and didn't get any alarms. I'm thinking that maybe it went down for just a moment and had trouble syncing back up. The ringing was not the vm alarm. The ringing was coming in on the line keys. It was displaying 500 on the display. I do understand that this could be a hard issue to track down. It may have just been a fluke thing. I will continue to monitor the system and see if it happens again. Thanks for your help

I dont think it was a fluke. More often lately I have noticed that systems without a CSU/DSU in plase are having hard to diagnose troubles. Samsung systems even though they dont state it should have a CSU in place. The next time they go down I would have one handy just incase.


Keep us posted
:thumb:

Does the CSU help keep the T1 stabalized? Just not sure what a CSU does. I will keep you guys posted. Thanks

I have installed 2 iDCS 100 systems recently. In both cases I tested the systems without a CSU and there were a lot of sync/line problems. Putting in a CSU cleaned up the line in both cases. I would not install a system without one. In addition, the telco can loop up the CSU to test the lines. I would put the CSU close to the system.

Sounds like installing the CSU/DSU might clean up my problem. Thanks guys for all your help.