Well, you have definitely done your homework. You are correct about the remote terminal; the lines with higher voltages are likely the ones coming from the remote. Unfortunately, the voltages you have measured aren't really out-of-line. The target voltage is 48 volts DC, +/- 10% at the premises. Very often, the voltage leaves the CO at 52 volts so that a typical copper loop can be compensated.

The lines that measure in the 30's do concern me, but I doubt that they would cause the trouble you are reporting. If anything, the problem would be low volume complaints, especially on conference calls.

As for AC voltage, the only time that should be present is during a ring cycle. If you are picking up tiny amounts, that can be attributed to AC induction from power lines. You will probably pick up much more between tip or ring to ground. Anything more than a few volts might be a problem. Even though ringing voltage is AC, it is at 30-40 Hz so measurements with a regular meter might not be accurate.

Tip is always grounded, even on the new pair gain equipment. It's a basic fundamental of POTS lines and if it changed, there would be millions of dollars worth of test equipment that would have to be thrown out the window.

Did you measure loop current? That's the real killer. You will need to place an ammeter in series with one side of each line while going off-hook to get an accurate measurement. This should be between 23 and 27 mA in a perfect world.

It is a bit ironic that these same lines didn't bother the Comdial system, but I am assuming that it was an old one. They were a lot more tolerant to line variations than today's equipment.

Ed Vaughn, MBSWWYPBX