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.

-TJ-