Has anyone even seen an intermittent issue where an 8 SLI and/or 16 SLI intermittently does not provide a power down (battery drop) when a CO line hangs up on an iDCS500R2 ?

System CO connection is via PRI and about 80 - 90% of the time the battery drops as it should on the SLI ports when the calling party hangs up. But every now and then it doesn't leaving our devices off-hook requiring the device to be powered down or unplugged to reset.

If you get on the circuit with a set you can hear the alternating high/low call dropped/hung up tone from the switch.

Power down timer has been increased to 5 seconds in an attempt to fix the problem to no avail.

All ports have power down option enabled, installer is stumped, Samsung even visited site at installer's request, still no luck even tracing back the root of the issue, whether it is coming from the switch or possibly the PRI, or maybe the SLI cards.

I've seen that happen when SLI's are called by another station but not from a trunk call. I guess the question I have is the PRI actually disconnecting correctly or are just certain channels not. Maybe the system itself isn't getting a proper disconnect on the PRI. I'm stumped as to what else it could be.

I've honestly wondered the same thing because I've tried to duplicate the problem in a controlled situation and can never duplicate it.

However, I've got a question I can't rationalize in my head, if the switch did not see a proper disconnect on the PRI why would I be receiving a high-low hangup tone?

Is it feasible to receive trunk release without a disconnect? Seems like they should be one and the same.

Do you have a copper trunk you could test the same switch with? What if any cards have you tried swapping? Sounds like this one may take a while to solve.

We've tried it with both SLI8's and SLI16's and have the same result.

I think I've got an old TRK C1 card in storage, I'll have to come up with a line to test with since we've gone almost exclusively PRI.

But one other thing I failed to mention in my original post, this system is networked to an iDCS100 via another TEPRI card and we have some incoming trunks from that 100 which uses regular copper trunks and we have had the same thing occur with incoming calls from that system too.

I really wish I had a way to put a logger on the system that could track the DC voltage on these lines when the problem happens. I've thought about looking at a couple of vendors who make PC interfaces that provide a mux of 8 or so DC inputs that can be logged to a PC. Then I could probably get a true picture of what is happening.

This is truly the proverbial Watched Pot Never Boils.

I am assuming that you do have SLT loop open set to yes in MMC 300?

Yes, and as an attempt of last resort we have also tried changing the ring type in 208 to see if it made any change in the problem.