Dsl & VOIP sharing wiring cable.

Discussion in 'Other Linksys Equipment' started by GML1943, Nov 9, 2005.

  1. GML1943

    GML1943 Guest

    When I built this house in 1976 I pre-wired all the rooms with 8 conductor (4 pair) phone cable. Currently pair 1 is phone line 1, and pair 2 is phone line 2/DSL. If I go with VOIP and plug Pair 1 into the VOIP adapter (after unpluging the line from the Phone Co Gray box (demarc.)

    The question is will the DSL signal in the cable cause interference in the VOIP line?

  2. leonardoh

    leonardoh Network Guru Member

    For DSL modems you need to put a DSL filter. The filter basically removes all frequencies that the modem uses so they don't go into the phones and cause interference or other problems.
    Anyway, you should already have filters in the phones plugged to your line 2. Do it if you haven't.
    What you could do is put a little box and separate from there 2 pairs.
  3. MacJube

    MacJube Network Guru Member

    DSL & VOIP interference on common wiring

    I'll disagree with Leonardoh and simply state the truth: If you're using good-quality cabling, you will get no interference on Line 1 (carrying your VOIP line) from Line 2 (carrying your DSL signal). It's simply because the output of your VOIP adapter is what's called a "POTS" (plain old telephone set) signal, exactly the same as your phone company's service.

    My guess is that you're using 4-pair Category 5 twisted-pair cable. The reason that the pairs are twisted is so that any generated interference (from DSL, or from the 90 Vrms telco ring signal) is "positive" in one segment of a twist, and "negative" in the next segment. So any generated interference is cancelled out in the adjacent pairs.

    If you're using "quad cable" (also known as "junk wire"), interference may be a problem, even if you don't have DSL. Two phone lines on quad cable cause the ring signal on one line to be audibly heard on the other line. Quad cable uses the red-green-yellow-black (4-wire) plus brown-orange-blue-white (8-wire) color scheme, whereas Cat3 and Cat5 twisted-pair uses blue, orange, green, brown pairs.

    My own house is wired with 3-pair Category 3 twisted-pair wiring, and I have Vonage service with a Linksys PAP2 VOIP adapter and DSL service on a standard Bell line, and I use the following scheme with no problems at all:

    Pair 1 (blue) -- Bell phone line with DSL
    Pair 2 (orange) -- PAP2 voice line
    Pair 3 (green) -- PAP2 fax line

    I've been running this setup for four months now with no problems whatsoever, and I only need DSL filters on Line 1 (which is carrying the DSL).

  4. Guyfromhe

    Guyfromhe Network Guru Member

    i can't forsee any issues myself with this setup either, particulariy if you use cat-3 or cat-5 though, i've had several lines running on junk wire before and never had any bleed through or sound quality issues and my modem connections were always at 52+k... though i'm running all cat5e for my telco now... regardless, it should be fine doing that if it's working now it should work with VOIP the only thing to concider when hooking an ATA to your home wiring is the length of the runs and the number of phones split off, an ATA is only able to provide so much voltage to the line most normal size houses/setups shouldn't have any trouble though...
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