Dialogic Cards Causing ISDN Channel Lockout?

Have you verified that your equipment and BT's are looking for the same line coding and frame formatting? For example, here is the U.S. my telco is sending B8ZS line coding and ESF frame formatting. So if my equipment isn't working with the same then there are issues. And since telco doesn't like alarms sitting there for an extended amount of time the circuit is placed out of service on their end to stop the alarming.

Is this Vocalcom product recently introduced? Or was it working for awhile and mysteriously stopped working with the telco circuit?

I had a discussion with BT about this. All my ISDN PRIs are to the ETSI standard. BT didn't believe this was the problem as: the system has been working and this is only happening occasionally and it is only some of the channels that are getting locked out. BT thought that it sounded like a 'Layer 3 problem', perhaps caused by:

- not taking the timing synchronisation from the BT Network

- a clock slippage problem.

I will get the first issue checked. However, for the 2nd issue apparently they would need to do a Trend test with equipment that supports 'parts per million' testing. I don't quite know what is involved here, but I am assuming they measure the clock slippage over a period to check that it is within bounds.

gregarican wrote:

Your local side should have some configuration setting for clocking source. If it is set to remote then that assumes telco provides the clocking. If it set to Local then it assumes that telco isn't providing the clocking. Perhaps that's something to check. If everything appears to be correct, which sounds as if your equipment should be looking for remote clocking that BT provides, then perhaps it's a quality of service issue on BT's end somewhere. In that case to prove your point it would help to sit on the circuit and passively monitor it for errors...

I have checked and the Dialogic cards have been set to take their clocking from a remote source. However, the Dialogic cards are also attached to some IP Gateways. It occurs to me that the IP Gateways should also be set to take their clocking from a remote source. I will get that checked.

When you talk about passively monitoring it, do you mean doing a Trend test?

I am not sure what a Trend test is. I was meaning CSU-type testing, which would indicate stats like Error Seconds, Bursty Errored Seconds, Path Code Violations, Line Code Violations, Controlled Slip Seconds, etc. Is your circuit coming in from BT via a T1/E1? If so how does the circuit come into your equipment? Is there a CSU that BT provides that you can plug into? Does the circuit come into some of your equipment that you can use to monitor things? It sounds as if the Trend test might be that latter option...