Why Telephone Equipment Interferes
The DSL signal can be "superimposed" on an existing phone line because the frequencies DSL uses are far above the frequencies used in voice conversations. Telephones won't even reproduces these frequencies. So the DSL signal doesn't interfere with phones...it's the other way around. The problem is that the circuitry inside virtually any device that connects to the phone line isn't designed with DSL frequencies in mind. DSL wasn't even around when most of these products were designed! If you think about it, telephone equipment is always "listening" to the phone line...after all, the phone needs to know when to ring, right? The answering machine needs to know when to pick up, and even your alarm system may have the capability to receive incoming calls (to arm the alarm remotely, check on status, etc.) Even if these features aren't enabled, the circuitry is still connected to the phone line.
This circuitry often "shorts out" the DSL signal--keeping you from getting a reliable DSL connection. Even if it doesn't, I'll guarantee it will as soon as you pick up a phone!
So something must be done to keep the telephone equipment from interfering with the DSL signal.
How To Properly Install DSL ServiceThere are two ways to keep your telephone equipment from interfering with your DSL signal: The easiest method is to put something between each piece of telephone equipment and the line to keep the equipment from interfering. The preferred method is to split the outside phone line, as it enters the house, into a DSL line and a voice line, and run separate wires to each.
A Proper DSL InstallationWay, way back, in the beginning of DSL. I was one of those first pioneering soles (and luck enough to be near a central office) that subscribed to a DSL service. It must have been...gosh, let me think...over two years ago now! (Isn't it amazing how fast DSL has caught on in a few short years?) Back in those "good old days", an actual human being would come to your house to perform the installation. The process is easy to describe. But, depending on the layout of your house, where the phone line came in, and where you wanted the DSL jack, the actual installation could be quite difficult. In essence, here's what the installer would do:
- He would start at the "demarc box" (a little box where the phone line comes into the house, see
Network Interface Device Boxes.) He added a little box (alternatively called a splitter, filter, low-pass filter, or technically a "ASDL NID POTS Splitter") to the wall next to the demarc box. In the demarc box, he disconnected all wires that went to the phones inside the house and moved them over to the new little box. Then he ran a jumper from the demarc box to the filter.
- He would then run a wire from the filter, around and through the house, to wherever your computer lived.
- He would put a jack on the wall there, mark it "DSL", plug the DSL modem into it, connect it to your computer, and even configure your operating system with the proper addresses and options and such to get you connection up and make sure it was working.
Of course, in my case, I wanted the DSL modem to go at my "head-end" in my garage where my hub and router already lived. I had the cables already ran and labled, and the installer just connected the wires, plugged in the jumpers, and turned on the modem. Still, it was nice to have a human being present to verify my wiring and make sure everything worked before the billing began.
So what I'm calling a proper installation involves actually "intercepting" the outside phone line before it enters the house, splitting it into a DSL side and a voice side, connecting the voice side to the inside phones, and then connecting the DSL sidedirectlyto one and only one device: the DSL modem.
The "Self-Install" Installation
As service providers ramped up installations of DSL, they realized that the limiting factor was the number of installation crews they could put on the road. So the service providers came up with a different way of doing things...one that didn't involve sending out an installer. The "self-install" kit contains several filters along with the DSL modem and an installation guide. The user is supposed to install a plug-in filter onalldevices that connect to the phone line. Then plug the DSL modem directly into the phone line.
In this scheme, the "raw" DSL/telephone line travels throughout the home. Telephone equipment doesn't interfere with the DSL line due to the filters that were added by the user. The DSL modem plugs into the raw DSL/telephone line, but doesn't interfere with telephone communications because it is designed not to.
The biggest problem with the self-install kit approach is the assumption that the person installing the kit can install filters on absolutely all equipment connected to the telephone line. This is usually not a problem...except for one important device: the security system. As explained previously, your security system may be connected to your phone line, and may cause problems with your DSL connection. Security systems are often connected to the phone line in a different manner than ordinary telephones because they have the ability to "seize the line." This feature allows them to interrupt any current phone call in order to dial out to the alarm company. Without this feature, an intruder would be able to keep the alarm from dialing out simply by picking up any inside phone and dialing a digit. (For more information on line seizure
click here.)
Unfortunately, this line seizure feature makes it impossible to use a standard self-install filter on the security system the same way it is used on other telephone equipment.The bottom line is that people that have line seizing security systemswill notbe able to self-install their DSL without some extra work.
When Self-Install Doesn't WorkUsers faced with the problem of a line-seizing security systems have several choices:- Option 1The simplest option is to instal a special version of the DSL filter that is designed for security systems at the RJ31X jack. Click
herefor purchasing information.
- Option 1
- If they have more than one telephone line coming into their home, have the service provider change the DSL to the line without the security system and install the self-install kit on that line. Alternatively, they could have the security company change the security system to the other, non DSL, line.
- Option 2
- If the security system is connected to the phone line via a
RJ31Xjack, and youdo not have monitoring or use any telephone accessto your security system, simply unplug the modular plug from the RJ31X jack. This will disconnect the alarm from the phone line and pass the phone line, unmolested, through to rest of your phones. The self-install kit should then be adequate.Warning: Doing this will prevent your security system from calling out in the event of an alarm.Any local bells or sirens should still work normally although you should test the system to make sure. Also, the alarm keypad may indicate a phone line problem. If your security system does not have an RJ31X jack, you can have your security company install one andthenunplug the security system from it. (The above warning still applies.)
- Option 3
- The preferred method involves running new wire from the demarc box to the location where DSL is required. See
A Proper DSL Installationabove. For step-by-step instructions, see
Running a New Wire For DSLbelow.
- Option 4
- Your last option will only work if you have only one phone line, but four wires (not just two) connected throughout your house. It may be a bit crude, but it should work, doesn't interfere with the operation of your security system, and should be fairly easy. See
Using the Second Pair for DSLbelow.
Running a New Wire For DSLFor this method, you will need the following:
- A weatherproof DSL splitter. See SU-649A1
here.
- Some telephone wire, either the old quad wire (
BE-1242A) or Category 5 style (
BE-1583A) is fine. Get enough to run from your demarc box on the outside of your house to the location of your DSL modem.
- A wall-mounted jack (
BE-410892WP) and voice-grade insert (
LE-41106RI) for the DSL jack. (Although there are other methods to mount a jack.)
- For tools, you'll need a flat blade screwdriver, pliers, and a 110 style punch-down tool.
Using The Second Pair For DSL
If your home is wired with four-conductor wire (the Red, Green, Yellow, Black stuff), and if you only have one phone line in use, andIFall four conductors are connected throughout all the intervening jacks (that's a big "if"), you can use the second pair to carry the DSL signal from the splitter to your dsl modem.
Please don't call or email us for help with this one, there is no way that we can know how your jacks are wired. Sometimes is takes a little of what I call "residential archeology". Go around with a flashlight and a medium straight blade screwdriver. Pull the plates and jacks of a few telephone jacks and see how they're wired. If there are two phone cables going into the jack, are all four wires from both cables connected to the screw terminals? If the yellow and black wires aren't, you'll have to connect them.
You'll need the following:
- A weatherproof DSL splitter. See SU-649A1
here.
- A two-line adapter (
here).
Connect the splitter out at your demarc box. The connections are as follows:
| Network Tip
| Incoming line Green
|
| Network Ring
| Incoming line Red
|
| Voice Tip
| To House line Green
|
| Voice Ring
| To House line Red
|
| Data Tip
| To house line Black
|
| Data Ring
| To house line Yellow
|
The black and yellow wires should now be carrying the DSL signal to the second line of your jacks. At the jack where the dsl modem is to be connected, plug in the two-line breakout plug and plug the DSL modem into line two.
The DSL Filter Designed for Alarm Systems
Z-A431PJ31X
Z-Blocker Self-Install DSL Alarm Filter |
|
- Simple plug-in installation.
- Compatible with all major ADSL, HPN, and alarm systems.
- Works with either RJ31X or RJ38X jack.
- Made by the same folks that most likely made your other self-install filters: Excelsus Technologies.
- Allows full-speed DSL operation...even when alarm system seizes the line.
- Does not disrupt or limit alarm system operation in any way.
- Manufacturer's cut sheet:
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FinallyI take great care in writing these tutorials, but I do make mistaakes sometimes. If you find one, please let me know and I'll correct it.
Also, I know from all the e-mail I get that you really like tutorials like this, and I truly enjoy writing them. Nothing forces anybody to buy from us, even though they might get all their information from us. I imagine some don't. But I'm also convinced that most do. Generally, our customers seem to be pretty loyal.
All we ask is that, if you find this information useful, that you give us a fair chance at your business when it comes time to buy.
Cheers,
Jeff
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by Jeff Fisher
