SLC failures, I think

[exverizon]

Customer has 2 lines on a SLC (type I don't know, I'm responsible for the station side). At times--during heavy call traffic, particularly, but not exclusively--a call comes in, she picks up, hears dialtone and not a caller. Happens on either line (they hunt), same thing. Callers who later get through report their call rang and rang, no answer, finally quit ringing. WIsh I could replicate the trouble at the NID to prove it, but it's always worked when I'm there (what a shock).

I've found issues on the station side that fix other problems; but it's my thought the SLC card is sometimes not performing proper call supervision and seeing the off-hook. Any insights?

 

[pbxn]

SLC-96 perhaps? Has the LEC frogged the card in the CEV yet?

 

[exverizon]

I'm betting it is a SLC-96: You can only answer a call when you go off-hook with a butt set BETWEEN ring cycles, and I recall that's a characteristic of those old things. If I knew the CEV combo and the cable pair, I'd swap 'em out myself! (Trick is to get Verizon to do it just for grins). Anyhow, you're right--frogging them would prove it out. Just have to see if what I've already done has any effect. I doubt it, though. Gotta get a vendor ticket put in to them...takes a couple days around here!

 

[pbxn]

I seem to remeber those 96 cards were picky from time to time. Usually my first coarse of action, if it was fed from a CEV.

 

[ISDNman]

Any chance she let the lines ring for 2+ minutes before she tried to answer. Most CO's have a timer and will cut off ringing after some (fairly long) time. If you cam back to your desk and pick it up right then you would get exactly that symptom.

Does she have call waiting/multiple call appaearences? If so then these callers may be ringing for quite a while, she then drop a previous call but does not get to them in time.

I guess the last thing to check, if she has a key system or PBX is to make sure that it detects ringing reliably - if it takes several rings (or even more) before the line shows as ringing then that would make it that much sooner that the call would time out . This would be consistent with it happening during the busy hour.

If you call in and the phone does not show ringing within 6 seconds then this could be thr problem. IN that case it could be due to the SLC, but ti also could be due to marginal ring detector design on the phone system.

You might see what happens if you place 3 calls into the system. If the 3rd call does not ring busy that is a problem

Good luck

 

[exverizon]

Unfortunately, her CPE consists of simple 2-line, non-key, plain-Jane phones. I know the CO will not ring a line forever, but she sits right at the station and usually picks up in a couple rings at most. I placed new AA batteries in the sets (the line LEDs had not been on previously), and cut out an unneeded--and old--protector in the loop (that was in a somewhat humid environment) because the service is fed from an outside telco 25-pr terminal with carbons. So redundant protection was eliminated.

I used to work in an area where one CO (a #5 ESS, I think) could have occasional trip ringing--even on copper pairs--which would not be audible to the caller (it continued to ring to them), but the called party would experience the trip. If they picked up anyhow, they'd get dialtone. We would have the CO replace the protector on the pair and the problem would be solved. But the odd thing here is there's no apparent trip. GRRR!

So far, I've not gotten a call from her in the last day or so--maybe the gremlins have found other fields to play in.