DSL Filters & Splitters

    High-quality DSL filters & DSL splitters for broadband access over conventional telephone lines.

    Overview  Products  Resources

    DSL Filter Innovation, Performance & Selection

    dsl-filtersInnovation led to our invention of the DSL filter back in 1999, and this forward-thinking mentality continues today, with high-quality xDSL filters that deliver the highest data rates and clearest phone conversations. Our xDSL filters/splitters are ideally suited for Central Office and Customer Premise Equipment applications, ensuring the following benefits:

    • Ensure clear, “echo-free” phone conversations.
    • Work with Caller ID despite the installation of three or more filters.
    • Are designed to coexist with alarm panels.
    • Meet ANSI, ETSI, and ITU performance standards demanded by many telephone companies.
    • Use high-gold RJ connectors that will resist corrosion, prevent phone-line noise, and preserve your modem’s data rate potential.

    Browse below for detailed information on our multi-service access node (MSAN) filter and broadband filter products. If you need assistance with a custom xDSL filter solution, you can always reach out to our product support team and we'll be happy to help.

    DSL Filter & Splitter Products

    MSAN Filters

    View our line of multi-service access node (MSAN) filters for Central Office applications.

    Broadband Filters

    View our line of broadband filters for Customer Premise Equipment (CPE) applications.

    Resources for DSL Filters / Splitters


    General FAQ

    • What are DSL filters and why do I need them?
      DSL uses the high frequency bandwidth of your existing telephone lines to transmit and receive data. Excelsus Z-BLOCKER® filters are “low-pass” filters, which means that they allow the low frequency signals (voice) to pass through, while blocking the high frequency signals (data) from traveling through the phone lines to your telephone. Without the filters, the high frequency data signals would be heard on your phone as static and noise, and would diminish the quality of your voice and data services. Excelsus filters protect your telephone voice quality and keep your DSL service operating at optimal speeds. Excelsus makes a variety of filters for different applications, such as wall-mounted phones and dual-line phones.

    • I have just signed up for DSL & my DSL provider sent me a self-installation kit with a modem and filters. What do I do with the filters?
      Install a filter for each telephone device in your home. Simply disconnect each telephone from the wall, plug a filter into the phone jack at the wall and plug the cord from the telephone into the phone jack of the filter. Do this for every analog device connected to your phone line. Analog devices include all answering machines, telephones, fax machines, Caller ID boxes, 56k modems, and cable or satellite television subscription boxes that connect to the phone line. Don’t forget the phone in the garage, basement, or outside by the pool! See this graphic image for a diagram of how this will look when it is set up.

    • Where can I purchase more Excelsus DSL Filters?
      Additional filters for Canada and the U.S. can be ordered online through Digi Key Corporation´s
      online store or can be ordered by contacting your local Pulse Networking Authorized Representative.

    • What if I don’t put a filter on every telephone device?
      Unfiltered phone devices can cause noise on all phones, even if they are filtered. This is because unfiltered phones can transmit low-frequency DSL artifacts back onto the phone line. The artifacts are within the voiceband frequency range, and pass through the filters as part of the voice signal. Therefore all phone devices must have filters.

    • Can I filter multiple devices with only one filter?
      Yes, the fax machine, telephone, answering machine and Caller ID box could all share the same filter by simply plugging a twin-jack adapter into the filter’s phone port. Then plug two or more devices into the adapter.

    • What filters should I use for my two-line phone?
      In two-line installations, one line carries voice and the other shares DSL and voice. Both lines require filters, otherwise the shared line will exhibit noise and reduced voice quality. Order the Excelsus Z-D250 “dual line” filter. It filters both lines for one or more phone devices sharing a single jack.

    • DSL is interfering with my alarm system. Do you make a filter for my alarm system?
      Yes. The Excelsus alarm panel DSL filter (model Z-A431PJ31X-A) uses advanced Z-BLOCKER® technology to protect the residential and small business alarm system telephone service (POTS) interface, which dials out to the alarm company in the event of an emergency. Without this protection, alarm panels on DSL or HPN lines may have difficulty reporting incidents. The alarm filter supports the alarm system’s ability to take custody of the phone lines (“line-seizure”) while maintaining the high-speed data link to DSL and HPN devices in the home. The alarm filter is compatible with every major home alarm system and interfaces with the alarm panel via the RJ31X – RJ38X (or Canadian equivalent) jack. The alarm filter won the prestigious Product Achievement Award at the ISC Expo’s New Product Showcase in New York in August 2001. Excelsus also offers a version with screw terminals (Z-A431EU). Excelsus alarm filters are available through licensed alarm service providers and security industry distributors. DSL customers, please contact your local alarm service provider for ordering information.


    Troubleshooting FAQ

    • Whenever my DSL modem is turned on, there is noise on the telephone. What is happening and how do I fix it?
      This problem can have several root causes:
      • Unfiltered phone devices can cause noise on all phones, even if they are filtered. This is because unfiltered phones can transmit low-frequency DSL artifacts back onto the phone line. The artifacts are within the voiceband frequency range, and pass through the filters as part of the voice signal. Therefore we recommend that all phone devices have filters.
      • Cross talk may be occurring in the standard flat cord that connects a telephone, fax machine, or other device to the wall jack. By placing a DSL filter at the jack where an analog device plugs into the wall, the device and flat cord will be isolated from modem activity.
      • Homes with twisted pair cable are protected from cross talk. Homes using standard flat cord or quad twisted cable have little or no protection against cross talk. The only solution for those homes is to have the DSL provider install a DSL Splitter where the line comes into the house to put the modem on its own isolated line.
    • I installed the filters and now my DSL data service is not working. What should I do?
      Excelsus filters should be installed on all of the analog telephone devices in your home. However, your DSL modem should be plugged directly to the jack, or the DSL/HPN side of the filter. Check to make sure that the cord from the DSL modem to the wall does not pass through the filter’s phone port; if the modem is plugged into the phone side of the filter, the DSL modem will not “sync” up. If you still have trouble with your service, contact your DSL provider for assistance.

    • After I installed the filters, my Caller ID service quit working. How can I fix this?
      Filters increase the capacitance (the stored electrical charge) on your phone lines. Caller ID works by sending a signal between ringing intervals via frequency shift keying, which can be affected by higher capacitance. If the capacitance is too high, the Caller ID unit will not be able to read the incoming signal. The Excelsus dynamic filter model Z-275P2J is activated only when the phone is off-hook, minimizing capacitance and allowing the Caller ID signal to pass through more easily. The dynamic Z-275P2J should also be used for all additional single-line phones beyond the first five.

    • I have two phone lines coming into my home. Why did line two go dead when I installed the filter?
      You’re probably using a single-line filter, which cannot pass line two. You need a dual-line filter (Z-D250P2J or Z-D250CWA) which isolates both line one and two from the modem.


    Technical FAQ

    • Why does Excelsus recommend the dynamic filter if I have more than five phones?
      Filters increase the capacitance (the stored electrical charge) on your phone lines. When there are more than five Excelsus filters on the phone line, the increased capacitance may cause noise and loud sidetone in telephone handsets. Increased sidetone occurs when your own voice is transmitted back to your own receiver louder than normal and may have an echo-like effect. It also reduces the volume at which your voice is transmitted to the party you’re speaking with. With increased sidetone, you may feel like you are speaking very loudly while the person on the other end of the line can barely hear you. Excelsus designed the dynamic Z-275P2J filter to actively filter only when the phone is off the hook, minimizing the capacitance that is added to the phone line. The dynamic filter is compatible with all Excelsus filters, so you can use a mixture of these models. Just be sure to use the dynamic Z-275P2J for all additional single-line phone jacks beyond the first five.

    • I have three or more phone lines and/or a PBX key system, which do not work with the filters. What can I do?
      Install one filter or DSL splitter ahead of all your telephones. This requires a separate wire pair to be run directly from the Network Interface Device (where the phone line connects to your home from the outside) to the phone jack connecting the DSL modem.

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