atcomsystems.ca/forum Forums TDM Business Telephone Systems NEC Telephones & Systems sv8100 pstn call dropouts

i have 2 sites with the same issue. they are both sv8100's one is v4 the other v5. the prob im experiencing is with a call in progress, intermittently the call will drop out, the sv8100 user's line key goes out, to get the call back the sv8100 user presses the line key to retrieve the call back, can only retrieve incoming calls, cannot retrieve the call on outgoing calls. contacted TAC but no joy, have replaced all cards and reprogrammed from scratch but no joy.has anyone experienced this fault before?????

Are you using a T1 or a PRI? I have seen this with clocking issues from the carrier.

no both systems are on pstn

I assume that you are in Australia where they call analog CO trunks PSTN trunks??

Can't say that I have seen this problem here in NZ on CO trunks.. Are your trunks served directly from the CO or via some sort of MUX unit??

yeah thats it! analog CO trunks, wasn't aware noone else called them pstn! i believe they are through a pair gain system, reported the issue to the carrier (telstra) but of course they said there was no problem with their gear

pstn = Public Switched Telephone Network.
CO = Central Office lines, a/k/a "copper" lines.
pots = plain old telephone system

Sounds like a timer issue or possibly a call supervision issue.

I would suggest measuring the voltages & loop current on those pots lines. The Mike Sandman site has great intructions on how to do this. High loop current over 32-35ma can cause weird things to happen in a phone system.

I've seen this on two other types of systems.

I might suggest you watch the user answer calls for a while - I don't know if it happens on a UX or SV but I recently solved this exact issue at several customers on several systems

to summarize their specific issue, and again, it may not apply here, either to the user or system:

- the user had line appearance keys
- the user should have simply "gone off hook" to answer the "ringing" inbound external calls
- but, the user pressed the ringing line key as the call came in
- this action set some sort of timer in the system and about 20 seconds in to the call the caller appeared to be placed on hold
- the caller is then in a loop too so to speak
- this then continues throughout that entire call even if transferred to another extension - every 20 seconds the caller is placed on hold by the system
- because of our "other system" experiences, we heavily train our users never to hit the line buttons (if installed) on inbound callers (just lift the handset)
- so I can't say we've even had the issue on NEC products, but it was driving me nuts on one specific other brand. We found the problem by watching the user operate the set
- ONE OTHER NOTE - in one case the user didn't even realize she was hitting the line - because of her "nails" she was hitting the key "inadvertently" at least a couple of times a day as she picked up the handset - she insisted she wasn't - we only were able to detect the button being pressed thru that system's equivalent to "DIM"

May not apply, but you really do seem to have tried everything else - maybe time to sit with her and have a chat, while keeping a sharp eye out on how she operates

yeah thanks, thats a good point. the issue has seemed to have dissapeared (touch wood) for now. had to make heaps of changes in the "80" mb's which seemed to have fixed the issue but might make a phone call and get someone to keep an eye on the person answering the phone