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I once had a CID issue on an NEC DSX. Support was adamant that they wouldn't help me until after I guaranteed them that there was a secure ground. In that case, it turned out to be the KSU but it showed just how important a good ground is when troubleshooting CID.

Sorry, guys. I'm not buying the "grounding" thing. CID data is sent balanced across tip and ring in the original Bell 212 format at 1200 baud. If grounding was really an issue, then how come it works on a single-line device with absolutely no reference to ground? My suspicion is that there is some form of solid-state protection device on the line(s). These have the tendency to squelch the data burst.

Ed here at the house we just have unground outlets (built in 50's) except for one outlet I installed for my computer that I ran new wiring to with ground. Using the un-grounded CID was all over the place, worked sometimes, sometimes didn't I tried all kinds of resets different KSU the whole 9 yards. When I got an extention cord and plugged it into my grounded outlet, no more CID problems. Has to do with the KSU not the way CID is delivered. Can't tell you why just know what happened. I thought it was a system flaw for quite awhile, until I said well this shouldn't matter but it did.

Going to add it still doesn't make sense since it's 2 and a ground to a step down transformer. I just know it cleared the CID issue I was having with 3 different ksu's and several phones.

I know why Bill and ED, but do to my poor way to explain the answer i will give a summary later today but in the mean time some smarter or quicker
VOICE (a clue) can do a much better job.

OK TJ, waiting for your answer. Doesn't make sense to me unless some noise (unheard) is being induced into the data stream without the ground.

Normally on cid BOX with analog line we say the unit is working ok.(true).

When you factor in the the the Server,KSU or other device which does a demod of the FSK signal to present to the output of the display unit it is in the form of a DIGITAL format.

Modern KSU takes analog signal(co line/voice) and turns it into a Digital format and is so designed to use the ground as part of the equation.

In your case Bill, the system works just fine other the the hit/miss CID function.

Why ? You think maybe the FSK is being over looked, or the Frequency of the shifts is just not being read to display the proper format.

I guess it could be a product of pay me now/pay me later as the lost of the ground applied to the KSU.

I would look at it as of DTMF tone distorted producing wrong numbers.

Yes, as you last posted the FSK signals are being destroyed by a compromise of the circuit so designated to process the CID function because the lack of grounding.

Thanks for the explanation TJ.

verizon came out yesterday and the tech said that he had no way of checking the caller id with out a single line phone. but he assured me that the problem in in the ksu because they have fios to the house and there is never a problem there. i thought they were pots lined but i was wrong. i will go out to the dmarc and install ksu there and see what happens

Easier to temporarily install an SLT there for testing...

Do what justbill told you.