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1.3 Line Sharing FAQ

Line Sharing refers to a ruling last year by the FCC that paved the way for competition for data services over your existing phone line.
This means that you are able to choose data (DSL) service from other companies apart from your local Telco, but avoid the installation of a second phone line at your premise.
Line sharing is regarded as critical for the success of an open DSL market.

edited by KeysCapt See Profile
last modified: 2002-07-22 19:56:23

A distributed filter, or micro-filter, is a small electronic component that fits between your phone line and a regular voice device, such as a phone, a fax, or any device with a regular modem such as a cable box, alarm system or digital TV.

When DSL (ADSL) is provided over voice lines, all devices in the house except the DSL modem must be connected through filters. The filter protects the phone devices from high frequency noise. They are low-pass filters. The filter is also there to protect the DSL signal from being contaminated by high frequency noise added by analog phone devices, answering machines, etc.

During a Line Sharing install, one important question is how many devices require filtering, as this determines how many filters are supplied with the install kits.

edited by KeysCapt See Profile
last modified: 2002-07-22 23:09:13

No, you don't. The cable installers will come out and install a hard line right into your home. Beware though, when you do this your monthly payment will normally be higher than if you do have cable TV service.

by McGruff3 See Profile edited by 2kmaro See Profile
last modified: 2002-03-11 02:22:41

For a LINKSYS Router:
  • In your browser, go to[] and login.

  • Go to the Status page, and write down the DNS numbers & the MAC Clone under the wan (Looks like:XX-XX-XX-XX-XX-XX)

  • Go to the Advanced tab and then Mac Clone, and type in the #, click Apply. Exit IE.

  • Go to Network Properties. You should have TCP/IP, and whatever else if you're networking. Click on TCP/IP.

  • Specify the IP as 192.168.1.[1-10]; a different IP for each machine.

  • Specify Sub Net

  • Go to Gateway -> type in

  • Go to DNS -> Enable
    -Host: Computer1
    -Domain: the name after your email [ie RCN.com]

  • Now type in those DNS #'s you wrote down. If there are three, all three are good, but the first two are needed.

    If you need additional help, post in the LinkSys forum here on the site.

    For OTHER Routers:
    Do the same as above, on your router's home page.

    by datatransfer See Profile edited by KeysCapt See Profile
    last modified: 2002-07-22 18:55:40

    There is (normally) no requirement for any inside wiring.. the DSL service comes over your existing phone signals. Your local Telco does not have to visit your house, saving at least one install visit and one home-sit for you.
    At present, Line sharing may still involve one visit from your CLEC to do the installation of the filters and the configuration of your DSL modem and verification of sync to the CO. In future, Line sharing is also expected to allow self installation for those who are willing to follow some technical directions.

    Covad, Rhythms and NorthPoint all currently offer Line sharing. Exact availability varies from CLEC and from market to market.
    In some cases (Rhythms, NorthPoint), the customer is currently able to specify they wish a Line sharing install. In other cases (Covad), Line sharing is the default if available and if the product chosen is ADSL.
    SDSL and IDSL requests are technically unable to share a line with voice, so will still be done as another line install.

    No. At least in the case of Covad, a distance estimate beyond 12000 feet, or a line that measures at beyond 15000 feet is rejected when ordering DSL.
    If a line is not of suitable quality, Covad will currently refuse to consider using any other lines (for example secondary phone numbers), as in 85% of cases the 2nd lines also fail the quality tests.

    A splitter is the alternative setup for DSL and Voice in the same premise .. it sits at the NID, or entry point of the line to the premise, and splits off the data portion of the signal so that it can be run cleanly through the house.
    Generally, splitters support full rate ADSL if available, whereas filters limit top speed to a megabit or so.

    Where a socket needs to provide both voice and DSL, a Y-Adapter can be used. Exactly as it sounds, this simply splits the socket into two, so that one can have a filter and a phone attached, and the other goes to the DSL modem.

    TeleSurfer ADSl and TeleSurfer Pro ADSL only.

    The expectation is that the install window will drop from 30-45 days currently to about 10 business days. You only need to be home for one visit: the one from the CLEC install technician.

    A Splitter would be instaled for end-users that have a home alarm system wired into the phone lines, or have a Telecommunication Device for the Deaf (TDD) installed. The filter install is the default.

    Since the data service is added to your existing phone line, it is critical that you correctly identify
    • the primary PHONE NUMBER at your premise
    • the exact list of phone related devices currently connected.
    • whether you have a home alarm system, TDD, or wall mounted phones
    • Whether you have caller ID or any premium telco services activated
    • The address of the premise as it appears on your telco phone bill
    • The name of the person or company as it appears on your telco phone bill
    If any of this information is missing or incorrect, the order can be delayed or even cancelled.

    In the case where your voice line is not provided by your local telco.. for example, you are in verizon territory but have local phone service through RCN, or through Sprint.. although the ILEC controls the physical line, the first layer of voice support is of course the company you ordered local service through.
    In these situations, Line Sharing may not be available to you, since currently the CLEC (for example, Covad) is required to have inked agreements for your area with not just the big Telco, but all the competitive voice providers as well!
    As of the time of writing (Q1 2001), the FCC and some state regulatory authorities are pushing the "baby bells" to upgrade their systems so that customers that have elected to use other voice companies for local phone service are not precluded from getting DSL. It is expected that this real block to getting DSL will be removed completely by the end of the year.

    During install, if sync cannot be obtained at the DSL jack, after filters are installed, the technician will try to obtain sync further backwards in the wiring, all the way to the NID if necessary. This will eliminate or identify house wiring problems that cause sync problems.
    If sync cannot be obtained at the NID, the Technician will call in to run a test to see if sync "noise" reaches the DSLAM at your CO or not. No noise at the DSLAM means a problem at the CO, most likely, your line has not been cross-connected to the CLEC DSLAM properly.
    If noise is heard at the DSLAM, but sync is not obtained, then the technician may report the install is technically not feasible, which means your order is cancelled. If the technician has CO access they may be able to further troubleshoot CO wiring issues, improving the speed at which the ILEC can resolve the problem.

    If sync cannot be obtained at the jack, then the technician may install a NID splitter, and run a new wire for the data.. this removes the need for microfilters.

    If sync is lost intermittently at the jack, then the technician may test at the NID to see if sync is stable there. If it is, a splitter may be installed to avoid the internal wiring problems of the house.

    Sync problems at the NID may require further work at the CO to isolate the problem to the loop (the line), in which case, the install is cancelled with a technically not feasible.

    Currently the ILEC is not obliged to condition voice lines in case they are of insufficient quality (load coils, bridge taps, moisture in the line, cross talk etc), to support CLEC ADSL.
    This means that the loop (line) success rate of line sharing installs may actually be lower than dedicated line installs.
    In the former case, you, the customer, are stuck with the quality of the copper you already have to the CO. It is unlikely the CLEC can convince the ILEC to improve that line.
    In the latter case (non line-sharing installs), the line is required to be of data quality to start with, thus the CLEC can request the ILEC fix many problems in order to get you installed.

    Your ISP should try to help you, but the reality is that there is little that can be done to complete your original order.
    You may be able to choose an SDSL product that requires a new (clean) line to be installed, as a replacement for your ADSL line-sharing request. Normally the price for these products will not be as competitive.
    It is possible that ILEC ADSL will still be available to you even if your CLEC and ISP was unable to get you line-sharing ADSL. The ILEC may be more motivated to fix line problems found during installation of their own DSL product.

    Line Sharing has been legally possible since the beginning of 2000. But, the requirement that CLECs must arrange complex access, pricing and troubleshooting agreements with every single Telco in their footprint means that there are signifcant barriers to entry of this market.
    Only the largest CLECs (Covad, NorthPoint and Rhythms) have made some progress with line sharing in some markets meaning that for most consumers, nearly a year after the FCC inked the rules, there is still no ADSL choice beyond the local Telco.

    Even for areas that are line sharing enabled, the CLECs have not yet put together with their ISPs self-install kits.. so a CLEC line-sharing order may still involve more visits (1) than a telco self-install order (0).

    Finally, line-sharing makes the CLEC DSL products look remarkably similar to the Telco products, but not only are they are priced higher, but involve the home visit. In addition, we can safely predict a higher percentage of install failures may be encountered vs the Telcos own ADSL product.

    Our view is it will be difficult for ISPs to sell the hidden advantages of line-sharing CLEC DSL products (reliability and quality of service) in the face of these visible disadvantages.

    Finally, the increasing ties between SBC and Covad and Verizon and NorthPoint means that two out of the big three DSL providers will really lack the incentive to push products that squarely compete with the ADSL equivalent offerings from the Telco.

    As at the time of writing, Q4 2000, it is predicted that by December 1st, you will not be able to place an order for Covad ADSL services at all.
    You must wait to be notified by the ISP that the CO is enabled for line sharing.. Covad are not installing ADSL as second line installs.

    A qualified "yes".

    IF the phone line is good from your home to the Central Office, and IF there is power to the Central Office, you will have phone service, much like you have phone service during many power outages. If, however, a line is down, or if there is no power to the Central Office and/or the Remote Service Unit (most have generators and/or battery backup), then you may well have no telephone service. The loss of "utility provided" electricity does not necessarily mean you won't have telco service, but it's not guaranteed, either.

    The ADSL service is much the same. If the ISP has power, and if the Central Office has power, and if the lines are good, and if your notebook is charged, or if your home network is on a major UPS or filtered generator, you might have both POTS and ADSL service.

    by edited by KeysCapt See Profile
    last modified: 2004-02-12 06:45:18

    Answer: No if installed properly With line sharing technology the voice and dsl share the same copper pair. The reason they can do this is because they are in two different frequency ranges that aren't close enough together to cause a noisy phone line. When a splitter is installed at your house or when you use micro filters, the signals are separated to the appropriate device i.e. phone or dsl modem.

    by dslquestions2 See Profile edited by DrTCP See Profile

    Important note: Up to 40% Of ISP's as of Feb. 2003 used line sharing to get provide you with DSL service (Michael Powell fcc, feb 2003 testimony house energy and commerce commitee).

    Line sharing is the process of the CLEC as mentioned in the FAQ providing DSL services through a single phone line. The line sharing rule insured that the CLEC has access to the dominant ILEC line (such as sbc,qwest,verizon,bellsouth) to provide DSL while allowing you to continue to use them on the same phone line. However as a result of a February 2003 decision regulations will be eliminated in 3 years. If the ILEC doesn't want to give access to the lines or charge the price that CLEC's are willing to pay then your internet access may suffer if the CLEC loses access to the line. One example is Covad, however ISP's such as
    Speakeasy use Covad instead of the ILEC sometimes. The solution is to check with your ISP as to what telephone provider the use to access your lines on the local loop. Then ask questions to the company on their access to the local loop via a contract or agreement. Changing ISP's in about 2 years(article written july 2004) maybe unburdensome to some but if you have a business if could mean changing email addresses and restructuring(changing router settings and individual pc settings).
    If you plan on keeping the same isp for years, be sure to get information. There are many CLEC's out there and independent isp's who may use the CLEC for access.

    by alligata See Profile edited by KeysCapt See Profile
    last modified: 2005-07-05 13:29:38

Also read About DSL for lots more information