TELECOM Digest OnLine - Sorted: Question About "Network Interface" Phone Jack

Question About "Network Interface" Phone Jack

wylbur37 (
24 Jul 2005 18:49:38 -0700

After living in the same place in New York City for years, I recently
moved to another place (also in New York City). The room I moved to
has an existing phone jack but it looks different from the old
square-ish ones I'm accustomed to. (The old ones consisted only of 4
terminals inside the case). This new one is rather rectangular and
has a label on the outside that says ...

Network Interface
Disconnect plug from this jack during installation and repair
of wiring.
Plug working phone directly into this jack. If phone operates,
fault is in wiring. If phone does not operate, call repair

When I opened the case, I noticed that the red and green wires (the
only ones that will be actually used by the telephone itself) are also
connected to a little circuit board whose most conspicuous component
is a yellow cylinder-shaped object (about 3/4" long and about 3/8"
diameter) with the following markings ...

0.47 MFD
+/- 10%

* What is the purpose of this circuit board?
* Is it really necessary? (How come the old-fashioned jacks
didn't have this?)
* What if I were to disconnect it?

Also, when I looked inside the jack itself (the hole where you would
plug the phone into), I noticed there's some strange-looking gunk
inside. It's clear-colored and has the consistency of rubber cement.

* Is this something that's supposed to be there?
* What is it used for?

Post Followup Article Use your browser's quoting feature to quote article into reply
Go to Next message: Danny Burstein: "ISPs as Censors (Canada) ("
Go to Previous message: Monty Solomon: "Now Playing on Apple's iTunes: Adult-Oriented Podcasts"
Next in thread: Tony P.: "Re: Question About "Network Interface" Phone Jack"
May be reply: Tony P.: "Re: Question About "Network Interface" Phone Jack"
May be reply: William Warren: "Re: Question About "Network Interface" Phone Jack"
TELECOM Digest: Home Page