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DSL-300T ADSL Modem User’s Guide
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Microfilters and Splitters
Most ADSL clients will be required to install a simple device that prevents the ADSL line from interfering with
regular telephone services. These devices are commonly referred to as microfilters or sometimes called
(inaccurately) line splitters. They are easy to install and use standard telephone connectors and cable.
Some ADSL service providers will send a telecommunications technician to modify the telephone line, usually
at the point where the telephone line enters the building. If a technician has divided or split your telephone line
into two separate lines - one for regular telephone service and the other for ADSL – then you do not need to use
any type of filter device. Follow the instructions given to you by your ADSL service provider about where and
how you should connect the Modem to the ADSL line.
Microfilters
Unless you are instructed to use a “line splitter” (see below), it will be necessary to install a microfilter (low pass
filter) device for each telephone or telephone device (answering machines, Faxes etc.) that share the line with the
ADSL service. Microfilters are easy-to-install, in-line devices, which attach to the telephone cable between the
telephone and wall jack. Microfilters that install behind the wall plate are also available. A typical in-line
microfilter installation is shown in the diagram below.
Microfilter Installation
Important: Do not install the microfilter between the Modem and the telephone jack. Microfilters are
only intended for use with regular telephones, Fax machines and other regular telephone devices.