TELECOM Digest OnLine - Sorted: Re: How Long Can a Telephone Extension Cord Be?

Re: How Long Can a Telephone Extension Cord Be?

Robert Bonomi (bonomi@host122.r-bonomi.com)
Tue, 16 Aug 2005 12:56:47 -0000

In article <telecom24.369.6@telecom-digest.org>, Phil McKerracher
<phil@mckerracher.org> wrote:

> John Levine <johnl@iecc.com> wrote in message
> news:telecom24.366.5@telecom-digest.org:

>> I think the limit is about 18,000 feet. Then you might have trouble
>> carrying DSL over it ...

> Correct, but that's the approximate limit for the total length from
> the switch to the telephone.

Strange, isn't it, that the limit for ISDN (with an extender) is over
_25,000_ ft? <grin>

In rural areas, for POTS service, 75,000+ ft of wire is not uncommon.

> Beyond that, the signal is typically attenuated too much, mainly by
> cable resistance, and gets buried in noise.

Circa 18,000 ft is a general practical limit for _DSL_ circuits, only.
*NOT* due to cable "resistance", by the way -- but rather due to the
cumulative effect of distributed capacitance, and the 'blurring' of
high-frequency signal transitions that occurs as a result thereof.

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