Correct, I don't have much of an interest in electricity beyond AC vs. DC.
Then you have chosen the wrong hobby, and you are wasting the time and good nature of those of us who have given you a second chance, and are trying to help nurture your interest and progress in the art of telephony.
There are many other electrical concepts beyond AC and DC that are absolutely essential to telephone theory. Resistance, capacitance, inductance, impedance, voltage, current, gain/loss, reactance, reluctance, crosstalk, grounding, bonding, coupling, balanced/unbalanced, to name a few. Relegating these concepts to the "I have no interest in..." pile is doing yourself, and us, a disservice. You, because you demonstrate a lack of dedication, and us, because we have better things to do than to try to encourage a dis-interested student.
I privately postulated to a few folks here, during the last go-round with you, that possibly there was a troll-like theme to your Q&A. I now am convinced.
Further, beyond the small world of telephony, it is also recommended to anyone even remotely involved in any electrical endeavor, that they understand the difference between GROUNDING and GROUNDED conductors, and how that distinction is applied to safety and correct operation of everything electrical that we come into contact with in the real world. You are advised to start studying THAT right away. The knowledge can only help you in the future.