LINE Port LoopCurrent question
Mango:
I have been having severe audio problems with the FXO port on my OBi110, but not when a phone is plugged directly into the POTS line. A tech from TELUS was here today and he found and fixed some damaged insulation (exposed copper) outside my house. That didn't solve the problem, though certainly a good thing to do.
While I was testing the problem, I noticed the LINE Port LoopCurrent was 56 mA. Then suddenly it dropped to 26 mA and the problem went away. The tech mentioned he was going to check the CO, so perhaps he did something there.
tl;dr: Can anyone explain what the LoopCurrent is measuring? Is 56 mA is actually a problem or just coincidence that I noticed it?
SteveInWA:
It's measuring the electric current flowing through the two-wire analog telephone circuit between your phone and the central office switch port, or your ATA, if it's a VoIP line. It should be between 23 and 27 milliamps (mA) when the phone is off-hook, and it should be zero or near-zero when on-hook. 56 mA is way out of range, and would definitely cause the severe distortion, and possibly damage your equipment. Perhaps the telephone company tech fixed something in the CO that was causing the problem.
Mango:
Thanks for confirming this. Unfortunately the problem has returned; now the LoopCurrent is 62 mA.
SteveInWA:
Did the tech test the loop current without the OBi in the loop? That would be the obvious "is it this, or is it that" test. If it's that high at the demarcation box, with all your premises equipment (phones and wiring) disconnected, then the telco has to fix it. If it goes up when the OBi is off-hook, then you've got a bad OBi. The same logic would apply to whatever else is connected in parallel to your phone line, like other phones, fax or answering machine, etc.
Note that you can't just hook up an ammeter to the two wires, with no telephones or other telco devices in the circuit. You'll overload your meter and not get a reading. You need a standard impedance load on the line to measure the current (the load is 600 Ohms in the USA, not sure about Canada).
Mango:
Unfortunately he did not. I only discovered the LoopCurrent after he left and the problem came back.
I just tested another OBi110; it also showed a LoopCurrent of 62 mA. I've been testing with the OBi connected directly to the demarc, so the problem is theoretically not some other device.
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