What is the role of a Network Interface Device in a ADSL connection?

Why the filter is not enough? What is the difference between them?

  • 1
    \$\begingroup\$ Perhaps provide a block diagram in the question? I know a bit about the concepts involved but I can't help if I have more inforation so I know exactly what you are refering to \$\endgroup\$
    – Joren Vaes
    Commented Sep 8, 2017 at 9:48

1 Answer 1


The NID is owned by the phone company, and represents the point of demarcation between what they are responsible for and what you are responsible for. It contains protective devices that suppress surges caused by lightning strikes and accidental shorts to power lines, etc. It also provides the means to easily disconnect the customer equipment and test the line.

In contrast, the filter is part of the customer equipment, and is primarily intended to separate the frequencies associated with the POTS service from the ADSL frequencies, and provide a clean termination for the latter, reducing the effects of "random" POTS wiring within the customer premises (e.g., extraneous echoes and crosstalk that would reduce the ADSL signal to noise ratio).


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.