atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's PRI issues on Nortel systems

We have PRI issues quite often on our Nortel phone systems here in Cincinnati. Our systems pop Alarm 75's all the time. This alarm means that the clock is in free run. Sometimes we get an alarm that states that the clock source has changed and we didn't change anything and the carrier has no record of anything changing. We set our clocking to Primary. We also get many minor violation alarms as well as critical alarms that mean the circuit has gone down. None of our other branches have issues with their circuits like we do and we don't program anything any different. I think this is an issue with the equipment at the CO. I wonder if we should be setting up our clocking here as Internal instead of Primary. Any thoughts? We have been battling this issue to the point that it is becoming such a nuisance. The problems that we have seen has been 99% of the time the carriers issue.

Well to me primary means you're supplying the clock, you need to slave off the CO clock.

Bill, in the Land of Norstar "Primary" means you are clocking off the network, in this case the CO. So, that setting is correct. If you go to "Internal" timing, you'll see major problems.

Has the system worked correctly in the past? If so, you can bet the problem is with the telco.

Thanks Larry, they all use just a little different terms.

This is not a problem with just one system. Many of our systems have this problem. We took over a service account on a BCM400 that has the PRI as Internal and the customer said that they very rarely have any issues.

Cincinnati Bell is the main carrier here. The majority of the switches are 5ESS switches. Does anyone have an idea as to why the Nortel systems would pop an Alarm 75 quite often? This is driving us crazy because the carriers say that the circuit looks clean but the systems keep generating an Alarm 75.

We have a customer that keeps getting calls cut off and the Norstar keeps popping an Alarm 75. Time Warner Telecom is saying that they see only time slips and Cincinnati Bell has not been there to check the smart jack. Could our issue with calls cutting off and time slips be a smart jack issue? How can I relay this to the TW tech?

Send a Loopback to TW let them see what is going on. You might have a bad COMBO card or T1 as well that is loosing sinchronization

If slips and only slips are being seen it can't be a Teleco problem, they supply the clock so they can't slip. Slips on a T-1 can only be caused by customer equipment. If the CO looses clock sync everyone does, not just one customer.